EXPLAINER: How real are Putin’s nuclear threats in Ukraine?


              FILE - In this video grab provided by RU-RTR Russian television via AP television on Thursday, March 1, 2018, a computer simulation shows the Avangard hypersonic vehicle maneuvering to bypass missile defenses en route to target. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (RU-RTR Russian Television via AP, File)
            
              FILE - In this photo released by Russian Defense Ministry Press Service, Russian nuclear submarines Prince Vladimir, above, and Yekaterinburg are harbored at a Russian naval base in Gazhiyevo, Kola Peninsula, Russia, on April 13, 2021. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (Russian Defense Ministry Press Service via AP, File)
            
              FILE - This image from video provided by the Russian Defense Ministry Press Service, a Tu-22M3 bomber of the Russian air forces flies over the Mediterranean after taking off from the Hemeimeem Air Base in Syria, on Feb. 19, 2022. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (Russian Defense Ministry Press Service via AP, File)
            
              FILE - In this handout photo released by Roscosmos Space Agency Press Service on Wednesday, April 20, 2022, the Sarmat intercontinental ballistic missile is launched from Plesetsk in Russia's northwest. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb.(Roscosmos Space Agency Press Service via AP, File)
            
              FILE - Deputy head of Russia's Security Council and chairman of the United Russia party, Dmitry Medvedev, second left, visits Totsk military garrison in the Orenburg region, Russia, Friday, Aug. 5, 2022. Dmitry Medvedev, further upped the ante Tuesday, saying that Russia has the right to use nuclear weapons against Ukraine if its aggression poses threat to the Russian statehood.(Ekaterina Shtukina, Sputnik, Pool Photo via AP, File)
            
              FILE - Russian recruits take a bus near a military recruitment center in Krasnodar, Russia, Sunday, Sept. 25, 2022. Last week, Russian President Vladimir Putin also raised the stakes by declaring a mobilization of reservists to beef up his troops in Ukraine that is aimed to call up at least 300,000. (AP Photo, File)
            
              FILE - Russia's President Vladimir Putin and Russian Defense Minister Sergei Shoigu attend the opening of the Army 2022 International Military and Technical Forum in the Patriot Park outside Moscow, Russia, Monday, Aug. 15, 2022. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (Sputnik, Kremlin Pool Photo via AP, File)
            
              FILE - This photo taken from video provided by the Russian Defense Ministry Press Service on Saturday, Feb. 19, 2022, shows a Zircon cruise missile being launched from a Russian navy's frigate during military drills. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (Russian Defense Ministry Press Service via AP, File)
            
              FILE - In this photo taken from a video distributed by Russian Defense Ministry Press Service, on Dec. 9, 2020, a Russian Tu-160 strategic bomber fires a cruise missile at test targets, during a military drills, Russia. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (Russian Defense Ministry Press Service via AP, File)
            
              FILE - The Russian nuclear submarine Dmitry Donskoy moored near Kronstadt, a seaport town 30 km (19 miles) west of St. Petersburg, Russia on Saturday, July 29, 2017. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (AP Photo, File)
            
              FILE - Russian Tu-22M-3 long-range bombers fly during the Victory Day military parade marking 71 years after the victory in WWII in Red Square in Moscow, Russia on Monday, May 9, 2016. Russian President Vladimir Putin has warned that he wouldn't hesitate to use nuclear weapons to ward off Ukraine's attempt to reclaim control of its occupied regions that Moscow is about to absorb. (AP Photo, File)