Shares of banks in the eurozone saw sharp declines on Thursday after Russian forces mounted a large-scale offensive against Ukraine and European Union officials announced new sanctions on Moscow. Europe’s banks—especially ones in Austria, France, and Italy—are the world’s most exposed to Russia. In the weeks leading up to the launch of  Thursday’s multi-pronged military action against Ukraine by Russian forces, they’ve been gripped by concerns that an invasion would trigger biting sanctions with potential impacts on their operations and on financial stability more broadly. The eurozone banks index, which reflects the performance of the largest banking sector firms in the 19 European countries that share the euro, was down 8.6 percent by 11:13 a.m. New York time, erasing all 2022 gains. Leading the losses among Italian banks was UniCredit, whose shares had plunged 13.5 percent by 11:38 a.m. New York time. UniCredit told Reuters on Thursday its Russian arm had very high …