A U.S. Patriot missile battery has arrived in Poland as part of an agreement to upgrade the NATO ally's air defenses, the U.S. embassy said on Monday, in a deployment likely to irritate neighboring Russia.The battery, manned by up to 150 U.S. troops, will be stationed for about one month four times a year in Morag, northern Poland, close to Russia's exclave of Kaliningrad. Its main mission is to train Polish military personnel. U.S. troops were unloading 37 railway cars of equipment on Monday, the embassy said. U.S. and Polish officials are due to visit the site on Wednesday and...