NATO fears the 9M729 system contravenes the 1987 Intermediate-range Nuclear Forces Treaty, or INF. The Cold War-era pact bans an entire class of weapons — all land-based cruise missiles with a range between 500-5,500 kilometers (310-3,410 miles), and the alliance says that the Russian system fits into that category.
"It is time now for Russia to come to the table and stop the violations," U.S. Ambassador Kay Bailey Hutchison told reporters in Brussels, on the eve of a meeting between U.S. Defense Secretary Jim Mattis and his NATO counterparts.
She said that if the system "became capable of delivering," the U.S. "would then be looking at the capability to take out a missile that could hit any of our countries in Europe and hit America."
Hutchinson later clarified her position in a tweet in which she said she was not talking about preemptively striking Russia. Rather, she said in the tweet that her point was: Russia "needs to return to INF Treaty compliance or we will need to match its capabilities to protect US & NATO interests."
Washington has shared intelligence evidence with its 28 NATO allies that Russia is developing the ground-fired cruise missile and that the system could give Moscow the ability to launch a nuclear strike in Europe with little or no notice.
Russia has claimed that U.S. missile defenses violate the pact. In the past, the Obama administration worked to convince Moscow to respect the INF treaty but seemed to make no progress.
Mattis said Tuesday that he intends to bring the issue up during the NATO meeting. After four years of diplomatic effort, he said, the U.S. is living by the treaty and Russia is not. He said there is a lot of concern about that at the U.S. State Department and on Capitol Hill.
"I'm going to lay out the situation," Mattis said during a news conference in Paris. "I want their advice as I return to Washington, D.C."
Hutchison said the U.S. doesn't want to violate the treaty but that Russia could force its hand.
"There will come a point in the future in which America will determine that it has to move forward with a development phase that is not allowed by the treaty right now," she said.
Washington wants its NATO allies to ramp up diplomatic pressure on Moscow, and NATO Secretary-General Jens Stoltenberg said that all allies are concerned by Russia's continued work on the system.
"Russia has not provided any credible answers on this new missile," said Stoltenberg, adding that the INF is a "crucial element" of trans-Atlantic security which is now "in danger because of Russia's actions."