The Russian Defense Ministry has confirmed the movement of nuclear-capable missiles into Kaliningrad, a tiny Russian exclave on the Baltic coast between Poland and Lithuania.
It said the deployment is part of routine drills with the tactical Iskander-M missiles, which have a range of around 500 kilometers, across Russia.
The ministry also said one of the missiles was deliberately exposed to U.S. spy cameras.
Western news and intelligence officials initially reported that Russia was moving the short-range Iskanders, and an Estonian radio report on October 7 said they were en route from St. Petersburg to Kaliningrad, formerly known as Koenigsberg, in a civilian transport ship.
Russia has frequently threatened to place a missile system in Kaliningrad, right on the doorstep of the European Union and NATO military alliance.
Russia's reasons for shipping the missiles to Kaliningrad "could be innocuous," a U.S. officials told the Reuters news agency. "They moved a similar missile system to Kaliningrad in 2014 for a military exercise.
"It could also be a political gesture -- a show of strength -- to express displeasure with NATO," the official said.
Tensions between Russia and the United States as well as other Western powers have escalated in the past two weeks since the collapse of a negotiated cease-fire in Syria.