By Idrees Ali
WASHINGTON (Reuters) - The Pentagon said on Monday it tested a conventionally configured ground-launched cruise missile with a range of more than 500 km (310 miles), the first such test since the United States pulled out of the Intermediate-range Nuclear Forces Treaty (INF).
The United States formally withdrew from the landmark 1987 pact with Russia on Aug. 2 after determining that Moscow was violating the treaty, an accusation the Kremlin has denied.
The treaty, which was negotiated by then-U.S. President Ronald Reagan and Soviet leader Mikhail Gorbachev, banned land-based missiles with a range of between 310 and 3,400 miles (500 to 5,500 km).
In a statement, the Pentagon said the test took place on Sunday at San Nicolas Island, California, and the missile hit its target after more than 500 km of flight.
The test would have been prohibited by the INF treaty, had the United States had not left it.
U.S. officials had said for a number of months that they planned to carry out the test in August. The United States plans to test an intermediate-range ballistic missile in November.
Moscow denies flouting the accord and has accused Washington of breaking the pact, allegations rejected by the United States.
The dispute is aggravating the worst U.S.-Russia friction since the Cold War ended in 1991. Some experts believe the treaty's collapse could undermine other arms control agreements and speed an erosion of the global system designed to block the spread of nuclear arms.
A Pentagon spokesman told Reuters that Sunday's test used an MK41 launcher, but the system tested was not the same as the Aegis Ashore missile defence system currently operating in Romania and under construction in Poland.
Russia's Defence Ministry did not reply to a Reuters request for comment sent outside normal working hours.
"Russia had alleged for years that the land-based MK-41 could launch Tomahawks and therefore would violate the treaty," said Kingston Reif, director for disarmament research at the Arms Control Association advocacy group.
"Even though this is the first test of the combination, Russia will no doubt claim vindication," Reif said.
U.S. Defence Secretary Mark Esper has said that while he is in favour of placing ground-launched, intermediate-range missiles in Asia, it could be years before such missiles are ready to be deployed.
(Reporting by Idrees Ali. Additional reporting by Polina Devitt in Moscow.; Editing by Chizu Nomiyama, Jonathan Oatis and Dan Grebler)