By Jonathan Landay
WASHINGTON (Reuters) - The United States is reviewing military options, including new intermediate-range cruise missile systems, in response to what it says is Russia's ongoing violation of a Cold War-era pact banning such missiles, the State Department said on Friday.
Washington is prepared "to cease such research and development activities" if Russia returns to compliance with the 1987 Intermediate-Range Nuclear Forces Treaty, State Department spokeswoman Heather Nauert said in a statement.
The warning was the Trump administration's first response to U.S. charges first leveled in 2014 that Russia has deployed a ground-launched cruise missile that breaches the pact's ban on the testing and fielding of missiles with ranges of between 500-5,500 kms (310-3,417 miles).
U.S. officials have said the Russian cruise missile is capable of carrying a nuclear warhead.
Russia has denied that it is violating the accord.
In the statement marking the treaty's 30th anniversary, Nauert said the United States "remains firmly committed to the INF Treaty and continues to seek the Russian Federation's return to compliance."
"The administration firmly believes, however, that the United States cannot stand still while the Russian Federation continues to develop military systems in violation of the treaty," she continued.
The administration is now "pursuing economic and military measures intended to induce the Russian Federation to return to compliance," said Nauert.
The measures, she said, involve a review of "military concepts and options" that include researching new ground-launched conventional cruise missile systems.
"This step will not violate our INF Treaty obligations," Nauert said. "We are also prepared to cease such research and development activities if the Russian Federation returns to full and verifiable compliance with its INF Treaty obligations."
(Reporting by Tim Ahmann and David Alexander; Editing by Doina Chiacu and Andrew Hay)