Ukraine-Russia crisis: What to know about the fears of war

U.S. combat vehicles arrive at the Mihail Kogalniceanu airbase, near the Black Sea port city of Constanta, eastern Romania, Friday, Feb. 11, 2022. The first U.S. convoy of Stryker combat vehicles and military equipment arrived in Romania from Germany, as part of a White House move to send 1,000 U.S. land troops to Romania, as it looks to bolster defensive forces on the NATO alliance's eastern flank. (AP Photo/Andreea Alexandru)