The mission amounts to the most significant deployment ever of US forces to Poland, which once was behind the Iron Curtain but is now an enthusiastic member of NATO.
Though Russia had expressed its strong opposition to having a US military installation close to its border, there was no initial reaction from Moscow to the arrival of the missiles - perhaps an indication that it wants to play down the matter after failing to stop the deployment.
Andrew Paul, a spokesman for the US Embassy in Warsaw, said the battery arrived on Sunday at a base in Morag, a town in northeastern Poland just 60 kilometers from the Russian exclave of Kaliningrad.
Russian Foreign Minister Sergei Lavrov said in January, when the location was announced, that he couldn't comprehend the need "to create the impression as if Poland is bracing itself against Russia." The Patriot garrison was a Polish condition for a 2008 deal with Washington to host a long-range missile defense base meant to protect the US and Europe from feared Iranian attacks. That plan, developed and negotiated by the Bush administration, angered Russia and was later reconfigured by President Barack Obama.
Bush's envisioned missile defense interceptors were separate from the Patriots missiles, which have a shorter range and have not provoked Russian anger as greatly as the missile defense plan had.
In the reconfigured missile defense plan, Poland is still expected to host a missile defense base, but not until about 2018 and one on a smaller scale than that envisioned by George W. Bush.
The US military has previously carried out training exercises in Poland, and has also trained the Polish air force to operate F-16 military fighter planes, which Poland bought to modernize its military.
But Paul said the Patriot garrison involves a longer time commitment than anything before, and marks "the first continuing presence" of American soldiers and equipment in Poland.
The missiles were transported by rail from a US base near Kaiserslautern, Germany, and will rotate in and out of Poland along with 100 to 150 American soldiers for the next two years.
Poland has expressed interest in possibly acquiring some of the US missiles in the future, though no deals have been sealed yet.
