Russia attacks as Putin warns world; Biden vows to hold him accountable

Russian President Vladimir Putin attends a wreath-laying ceremony at the Tomb of the Unknown Soldier, near the Kremlin Wall during the national celebrations of the 'Defender of the Fatherland Day' in Moscow, Russia, Wednesday. The Defenders of the Fatherland Day, celebrated in Russia on Feb. 23, honors the nation's military and is a nationwide holiday. (Alexei Nikolsky, Kremlin Pool Photo via AP)

People queue for fuel at a gas station in Sievierodonetsk, the Luhansk region, eastern Ukraine, on Thursday. (AP Photo/Vadim Ghirda)

In this handout photo taken from video provided by the Ukrainian Presidential Press Office, Ukrainian President Volodymyr Zelenskyy addresses to the nation in Kyiv, Ukraine, Thursday. Zelenskyy declared martial law, saying Russia has targeted Ukraine's military infrastructure. He urged Ukrainians to stay home and not to panic. (Ukrainian Presidential Press Office via AP)

This photo shows a view of the city of Kyiv, Ukraine, Thursday, Feb. 24, 2022. Russian President Vladimir Putin on Thursday announced a military operation in Ukraine and warned other countries that any attempt to interfere with the Russian action would lead to "consequences you have never seen." (AP Photo/Emilio Morenatti)

A Ukrainian serviceman stands at his position at the line of separation between Ukraine-held territory and rebel-held territory near Svitlodarsk, eastern Ukraine, Wednesday, Feb. 23, 2022. U.S. President Joe Biden announced the U.S. was ordering heavy financial sanctions against Russia, declaring that Moscow had flagrantly violated international law in what he called the "beginning of a Russian invasion of Ukraine." (AP Photo/Evgeniy Maloletka)

In this photo taken from UNTV video, U.S. Ambassador to the United Nations Linda Thomas-Greenfield addresses an emergency meeting of the U.N. Security Council on Ukraine to deplore Russia's actions toward the country and plead for diplomacy, Wednesday, at U.N. headquarters. (UNTV via AP)

A flame is seen from an area near the Dnieper river in Kyiv, Ukraine, Thursday. Russian troops have launched their anticipated attack on Ukraine. President Vladimir Putin has cast aside international condemnation and sanctions, warning other countries that any attempt to interfere would lead to “consequences you have never seen.” (Mary Ostrovska via AP)

People watch a TV reporting the crisis in Ukraine during a news program at the Seoul Railway Station in Seoul, South Korea, Thursday. Russian troops have launched their anticipated attack on Ukraine. President Vladimir Putin has cast aside international condemnation and sanctions, warning other countries that any attempt to interfere would lead to “consequences you have never seen.” (AP Photo/Ahn Young-joon)

President Vladimir Putin of Russia declared the start of a “special military operation” in Ukraine on Thursday, after months of speculation about Russia’s intentions as it massed tens of thousands of troops on Ukraine’s border.