By Chuck Mikolajczak NEW YORK (Reuters) – U.S. stocks dropped more than 1% on Thursday, with investors gravitating toward defensive sectors and safe havens such as bonds and gold as geopolitical tensions heightened between Washington and Russia over Ukraine. U.S. President Joe Biden said there was every indication Russia was planning to invade Ukraine in the next few days and was preparing a pretext to justify it, after Ukrainian forces and pro-Moscow rebels traded fire in eastern Ukraine. Russia accused Biden of stoking tensions and released a strongly worded letter saying Washington was igno…