Russia has again accused the United States of lying about its deployment of antimissile systems in Europe, as Washington repeated its findings that Moscow was violating a key arms-control treaty.
The caustic comments by Russia's Foreign Ministry on April 29 followed the release of the State Department's annual arms-control compliance report.
The report, issued earlier this month, asserted for the fourth consecutive year that Russia had developed a ground-launched cruise missile in violation of the Intermediate-Range Nuclear Forces Treaty (INF).
Signed in 1987, that agreement, known as the INF, eliminated an entire class of cruise and ballistic missiles in Europe and is considered a bedrock treaty for U.S.-Russian arms control.
In its remarks, the Foreign Ministry rejected U.S. accusations, and repeated past assertions that the deployment of the so-called Aegis Ashore system in Romania and Poland contradicted the treaty provisions, something Washington has denied.
"Washington is providing deliberately false information about its 'fulfilment' of obligations under the INF treaty. For years, the United States has been simply ignoring Russia's serious concerns," the ministry said in a statement.
The Aegis Ashore deployment "is an undeniable fact that this is a gross violation of obligations in the INF treaty," it added.
The United States first formally accused Russia of developing a missile in violation of the INF back in 2014, though intelligence experts said the system had been under development for several years prior to that.
Last year, with Russia demanding the United States provide more technical evidence to back up its assertions, U.S. officials for the first time called a special meeting of technical experts to try and resolve the impasse, but it failed to clear up the dispute.
Then, in March, the vice chairman of the U.S. Joint Chiefs of Staff told Congress that Russia had begun deploying the weapons. General Paul Selva said it had violated the "spirit and intent" of the treaty and that it posed a threat to NATO.
In the 2017 U.S. report, the State Department's Bureau of Arms Control and Verification also provided several small hints at what the exact missile system was.
The bureau said it had provided Moscow with specific manufacturing details, and had given Russia the dates and coordinates of Russian tests of the cruise missile.
And for the first time in its public reports, the U.S. said the missile system was distinct from another ground-launched cruise missile -- the R-500, also known as SSC-7 -- or an intercontinental ballistic missile known as the RS-26.
Some arms-control experts have argued that the system, which is allegedly violating the INF treaty, is in fact based on the Iskander, a highly functional system of launchers and missiles whose recent deployment to Kaliningrad has worried European NATO members.
If the violating system turned out to be an Iskander, experts say the entire Iskander system would have to destroyed under treaty rules, something Russia would never agree to.
Steven Pifer, an expert at the Brookings Institute, a Washington think-tank, argued that the United States should press Moscow to comply, but not by deploying its own medium-range missile in Europe, which would destroy the treaty and which some Republicans members of Congress have called for.
Instead, Pifer said, Washington should consider putting conventional B-52 or B-1 bombers back into operation in Europe as well as increasing patrols of naval ships and submarines carrying conventionally armed sea-launched cruise missiles in the North Sea.
He also suggested that the United States should share more details with countries neighboring Russia, like Sweden, Finland, and China, to demonstrate that they are at risk from a new Russian missile.
"The United States needs leverage to persuade the Kremlin to come back into compliance," Pifer, a former U.S. ambassador to Ukraine, wrote in an op-ed published on April 26.
More U.S. conventional weapons in Europe "would be a countervailing measure that would offset the military advantages that Russia hopes to secure by its violation. Getting third countries to beat up on Moscow would raise the political and diplomatic costs," he said.