US troops in camouflage and full gear crossed from Germany into Poland in armored vehicles and jeeps on Thursday and headed to a base in the city of Zagan, 40 kilometers east of the border, where they will be deployed as part of a NATO deterrence force. The move came after infantry, armor, air, engineering and artillery forces from NATO member nations completed an exercise on Polish territory. The US force is the first to be placed permanently in the country, which is bordered by Ukraine, Belarus and Latvia in the east. It is not clear whether US President-elect Donald Trump will back the Pentagon's decision to deploy the troops. On Thursday, Russia claimed that the American military presence in Poland is a threat to its national security.