Ukraine-Russia crisis: What to know as tension grinds on


              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Vice President Kamala Harris meets with NATO Secretary General Jens Stoltenberg, left, during the Munich Security Conference, Friday, Feb. 18, 2022, in Munich. (AP Photo/Andrew Harnik, Pool)
            
              People pass by an unexploded missile fired by pro-Russian separatists in Ukraine's east and taken to Kyiv as a reminder of war, in Kyiv, Ukraine, Friday, Feb. 18, 2022. Russia has announced massive nuclear drills while Western leaders grasp for ways to avert a new war in Europe. Tensions are soaring after unusually dire U.S. warnings that Moscow could order an invasion of Ukraine any day. (AP Photo/Efrem Lukatsky)
            
              Members of the Joint Centre for Control and Coordination on ceasefire of the demarcation line, or JCCC, take forensic photos of a crater and damage to a house from artillery shell that landed in Vrubivka, one of the at least eight that hit the village today, according to local officials, in the Luhansk region, eastern Ukraine, Thursday, Feb. 17, 2022. U.S. President Joe Biden warned that Russia could still invade Ukraine within days and Russia expelled the No. 2 diplomat at the U.S. Embassy in Moscow, as tensions flared anew in the worst East-West standoff in decades. (AP Photo/Vadim Ghirda)
            
              Russian Foreign Minister Sergey Lavrov attends a joint news conference with Greek Foreign Minister Nikos Dendias following their talks in Moscow, Russia, Friday, Feb. 18, 2022. (Maxim Shemetov/Pool Photo via AP)
            
              Ukrainian National guard soldiers guard a mobile checkpoint together with the Ukrainian Security Service agents and police officers during a joint operation in Kharkiv, Ukraine, Thursday, Feb. 17, 2022. Fears of a new war in Europe have resurged as U.S. President Joe Biden warned that Russia could invade Ukraine within days, and violence spiked in a long-running standoff in eastern Ukraine that some fear could be the spark for wider conflict. (AP Photo/Evgeniy Maloletka)
            
              FILE - In this handout photo taken from a footage released by Russian Defense Ministry Press Service on March 26, 2021, a Russian nuclear submarine breaks through the Arctic ice during military drills at an unspecified location. Russian President Vladimir Putin on Friday hailed the military's performance during recent Arctic drills, part of Moscow's efforts to expand its presence in the polar region. Russia is planning massive drills of its strategic military forces that provide a stark reminder of the country's nuclear might. The Russian Defense Ministry announced the war games on Friday amid Western fears that Moscow might be preparing to invade Ukraine. (Russian Defense Ministry Press Service via AP)
            
              FILE - In this file photo taken on June 24, 2020, Russian RS-24 Yars ballistic missiles roll in Red Square during the Victory Day military parade in Moscow, Russia. Russia is planning massive drills of its strategic military forces that provide a stark reminder of the country's nuclear might. The Russian Defense Ministry announced the war games on Friday amid Western fears that Moscow might be preparing to invade Ukraine. (AP Photo/Alexander Zemlianichenko, File)