Telegraph - Russia has covertly deployed a new, fully operational cruise missile in an apparent violation of an arms control treaty, US officials have claimed.
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 US 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 US election.
Moscow now seems to be testing the new president, however. A Russian spy ship was spotted off the US East Coast on Tuesday,according to Fox News, the first such incident since Mr Trump took office.
An official told Fox the US was monitoring the progress of the ship but did not find it to be "a huge concern".
Senior Republicans, including Senator John McCain, have been pleading with Mr Trump to take a firmer line with Mr Putin. Links between Mr Trump's senior aides and the Russian government have already proved problematic.
Michael Flynn, the president's national security adviser, resigned on Monday night after allegedly misleading top officials about his conversations with Sergey Kislyak, the Russian ambassador.
The two reportedly discussed US sanctions on Russia in December, despite the fact that Mr Obama was still president. Mr Flynn initially denied sanctions had been discussed, before reversing course.
The acting attorney general warned the White House last month that the retired general could be vulnerable to Russian blackmail, according to the Washington Post.
Rex Tillerson, the secretary of state, was questioned during confirmation hearings about his close ties to Russia during his time as chief executive of ExxonMobil, though he went further than Mr Trump has in criticising the Putin regime.