Barack Obama has accused Russia of violating a 1987 nuclear treaty signed by Ronald Reagan and Mikhail Gorbachev, declaring the breach to be "a very serious matter".
According to the US president, Russia tested a new cruise missile in contravention of the Intermediate-Range Nuclear Forces (INF) Treaty that came into force in June 1987.
White House officials confirmed that Obama had notified the Russian president Vladimir Putin of US objections to the tests by letter on Monday.
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The claim comes at a "highly strained time" between the US and Russia, The Guardian says, and brings into the public sphere "allegations that have simmered for some time".
The Cold War treaty was designed to eliminate ground-launched missiles with ranges of 500 to 5,500 km (310 to 3,400 miles), Reuters reports.
"This is a very serious matter which we have attempted to address with Russia for some time now," a White House official said in a statement.
No details were given on when and where the violation occurred, but the New York Times reported in January that the US had warned Nato that Russia was testing a new missile.
According to officials, Russia may have been testing the cruise missiles since 2008, but it was only in 2011 that the Obama administration concluded that they were a "compliance concern".
In May last year, Rose Gottemoeller, the State Department's senior arms control official, first alerted Russia to US objections to the tests, but this is the first time they have been made public.
Nato's top commander, Gen. Philip M Breedlove, says that such violations require a response, the New York Times reports.
"A weapon capability that violates the INF, that is introduced into the greater European land mass, is absolutely a tool that will have to be dealt with," he said in an interview in April. "It can't go unanswered".
Daryl Kimball, executive director of the Arms Control Association, a Washington-based research and advocacy group described the development as "disturbing".
