VILNIUS—The United States is concerned about the flow of Middle Eastern and African migrants from Belarus into Lithuania, a U.S. diplomat said. Lithuania began building a 320-mile razor wire barrier on its border with Belarus on Friday after accusing Belarusian authorities of flying in migrants from abroad to send illegally into the European Union. “We are watching it very closely and with concern,” said U.S. Deputy Assistant Secretary of State George Kent in an interview with Lithuanian news website 15min.lt, published on Sunday. He said the “pressure tactic” is comparable to migrant flows from Russia to Finland and Norway in 2015. “That’s something that we call on Belarusian authorities to stop—intentionally pushing migrants from other countries to the Lithuanian border,” said Kent. By Andrius Sytas in Vilnius