Moscow has accused the United States of ratcheting up military tensions by testing its first ground-based cruise missile since withdrawing from a three-decades-old arms treaty with Russia earlier this month.
Deputy Foreign Minister Sergei Ryabkov was quoted by the TASS news agency on August 20 as saying the test-firing of a conventional ground-launched cruise missile in California was "a cause of regret."
"The U.S. has obviously taken a course towards escalation of military tensions. We won't react to provocations," Ryabkov said.
The United Sates officially withdrew on August 2 from the 1987 Intermediate-Range Nuclear Forces (INF) Treaty that banned ground-launched cruise and ballistic missiles with a range between 500 and 5,500 kilometers.
The United States and the Soviet Union deployed such missiles around Europe during the Cold War, but they were seen as acutely destabilizing because of their short flight times.
The INF Treaty did not ban intermediate-range missiles launched from sea or air.
The U.S. Department of Defense said on August 19 that a day earlier it had test-fired the cruise missile at San Nicolas Island, of the California coast near Los Angeles.
"The test missile exited its ground mobile launcher and accurately impacted its target after more than 500 kilometers of flight," the Pentagon said.
President Donald Trump on February 1 announced the United States planned to pull out of the agreement following a six-month withdrawal period after accusing Russia for years of violating the pact.
The United States said Russia had developed and tested the 9M729 missile, also known as the SSC-8.
Moscow has both denied the allegation and asserted that U.S. missile-defense systems in Eastern Europe violated the treaty -- a claim rejected by Washington.
Russia suspended its participation in the INF Treaty following Trump's February statement but has yet to confirm a test.
The demise of the treaty has stoked fears of a new arms race between the United States and Russia.
"Developing and fielding U.S. INF Treaty-range missiles is militarily unnecessary," said Kingston Reif, director for disarmament and threat-reduction policy at the Arms Control Association, a think tank in Washington.
In an e-mail sent to RFE/RL, Reif said it "would force difficult and contentious conversations with and among allies about where to base them, and would likely prompt Russia and China to take steps that would increase the threat to the United States and its allies."
Russian President Vladimir Putin has said Russia would deploy ground-based intermediate missiles in regions where the United States placed them.
Frants Klintsevich, a member of the Russian Federation Council's Defense Committee, also criticized the launch, saying the country's response would be quick and possibly "asymmetrical."
"We will, obviously, do all that we can in the shortest possible time not to allow the U.S. to achieve superiority in these types of weapons," he told state media after the U.S. missile launch.
The Russian senator claimed a launch so soon after the treaty's end showed the United States violated the agreement "by continuing to produce such a class of missiles."
However, production of intermediate-range missiles wasn't banned, just their launch from the ground.
The missile test-launched on August 18 was likely taken from a destroyer or another warship and put on the back of a trailer, said Tom Karako, a missile specialist at the Center for Strategic and International Studies in Washington.
"It is not about the missile, it's about from where it is launched. We have been launching it from sea [for decades]. Folks can spread propaganda and all they want and misinformation, but we are on the other side of the treaty now," Karako said, referring to Klintsevich's statement.
The Pentagon will likely do more tests as it seeks to modify the sea- and air-based missiles for mobile ground launches, he said.
The Pentagon said it would use the data collected from the August 18 launch to inform the Defense Department's "development of future intermediate-range capabilities."