U.S. officials have reportedly acknowledged that Russia has tested a new ground-launched cruise missile, in apparent violation of a 1987 treaty banning the testing, production, and possession of medium-range missiles.

However, The New York Times reports that White House officials are not yet ready to formally declare the tests to be a violation of the treaty signed by former U.S. President Ronald Reagan and Soviet leader Mikhail Gorbachev.

The Times reported that Rose Gottemoeller, the State Department's senior arms control official, informed NATO about the tests at a closed-door meeting in Brussels earlier this month. The paper also reported that the Russian tests may have begun as early as 2008, but U.S. officials did not have enough information to consider the missiles a compliance issues until much later.

The issue of compliance centers on the missile itself, called the RS-26, which has been tested at both medium-range and intercontinental range. The small number of intercontinental tests qualifies it as a long-range system under the terms of the New START treaty negotiated in 2009.

Medium range missiles are defined as ground-launched ballistic or cruise missiles capable of flying 300 to 3,400 miles. Intercontinental missiles are capable of flying beyond that range.

Republicans have called on the White House to share any intelligence on suspected violations of the 1987 treaty with Congress and have urged the administration to be more aggressive in holding Russia to its terms.

"Briefings provided by your administration have agreed with our assessment that Russian actions are serious and troubling, but have failed to offer any assurance of any concrete action to address these Russian actions," Reps. Howard McKeon, R-Calif., and Mike Rogers, R-Mich., said in a letter to President Obama in April. McKeon chairs the House Armed Services Committee, while Rogers chairs the House Intelligence Committee.

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