By Idrees Ali and Phil Stewart WASHINGTON (Reuters) -The United States will send 3,000 additional troops to Poland, Poland’s Defence Minister said late on Friday, confirming an earlier Reuters report, as Russia held military exercises in Belarus and the Black Sea following the buildup of its forces near Ukraine. The additional troops will be sent to Poland in the coming days, four U.S. officials told Reuters on Friday. The deployment comes as Washington steps up warnings that Russia could be poised to invade Ukraine. Russia denies it plans to invade, saying it is defending its own security aga…