The move came as relations between Washington and Moscow dropped to a new low after US national security agencies accused Russia of using cyber attacks to influence the November 8 presidential election.
Hundreds of US tanks and other heavy military equipment arrived at a seaport in northern Germany on Friday to be shipped to Poland and eastern Europe as part of a NATO build-up which has alarmed Russia.
The move comes as relations between Washington and Moscow dropped to a new low after US national security agencies accused Russia of meddling in the presidential election in favour of President-elect Donald Trump. Ties were already strained by Russia's annexation of Crimea from Ukraine and differences between the countries over the war in Syria.
The military equipment will be used by some 4,000 American troops being deployed to the region. Polish forces will join US troops in military exercises at the end of the month.
NATO said the exercises with Poland have been planned for a while and are purely defensive. However, Russia has said they are aggressive in nature.
"Everybody should realise, this is transparent and this is just showing the strength and the cohesion of the alliance and the US commitment to maintain the peace on the continent," US Major General Timothy McGuire said on Friday.
Canada, Britain, and Germany are also deploying up to a thousand troops each to the region. They claim that these numbers are modest compared to the 330,000 soldiers which they say Russia has amassed on its western border.