U.S. Officials are claiming Russia has covertly deployed a new, fully operational cruise missile in an apparent violation of an arms control treaty.

Former U.S. President Barack Obama wrote to President Vladimir Putin after Russia tested the missile in 2014, contending that the test violated the landmark 1897 accord that banned the U.S. and Soviet Union from using intermediate and shorter-range missiles and helped bring the Cold War to a close.

The Russians appear to have disregarded the warning, and the missile has now been deployed according to the New York Times.

Administration officials told the newspaper that Russia has one battalion of the missile at a test site in Southeastern Russia, while a second has been moved to an operational base.

Donald Trump will now be tasked with responding to Russia’s decision to deploy the prohibited missile.

He repeatedly declined to criticise Mr Putin throughout the campaign and the early weeks of his presidency, even as many senior US officials lambasted the Kremlin for intervening in the U.S. election.