The United States said Thursday it would sell anti-tank missiles to Kosovo, toughening the defenses of the breakaway region even as tensions ease with Serbia. The State Department said it agreed to a request by Kosovo to buy 246 Javelin missiles — a key weapon provided by NATO to Ukraine to destroy the armored vehicles of Russian invaders. With related equipment, the sale is worth $75 million, the State Department said. The deal “will improve Kosovo’s long-term defense capacity to defend its sovereignty and territorial integrity to meet its national defense requirements,” a State Department statement said. Congress can still block the sale, although it is unlikely to do so. The sale comes days after Kosovo followed Serbia’s lead in letting in vehicles with Serbian license plates that do not cover up national symbols, ending a lengthy dispute. Tensions flared last year after Kosovo installed mayors in ethnic Serb northern areas following elections that were widely boycotted. Violent protests erupted, leading NATO to send more personnel, and the United States briefly accused Serbia of a troop buildup. Kosovo, which counts 120,000 Serbs among its 1.8 million people, declared independence from Serbia in 2008, in a move Belgrade has never recognized. Despite its historic support of Kosovo, the United States has grown frustrated by the hardline approach of Kosovo Prime Minister Albin Kurti.