MOSCOW, March 8 (Reuters) - Russia may suspend nuclear arms inspections set down in a treaty with the United States in reaction to Western sanctions over Ukraine, Russian news agencies quoted an unnamed defence ministry source on Saturday as saying.
The source said the ministry was studying the possibility of suspending on-site inspections agreed in the Strategic Arms Reduction Treaty (START) between Moscow and Washington.
The United States suspended military cooperation such as joint exercises and port visits with Russia on Monday as Washington sought ways to punish Moscow over its intervention in Ukraine without escalating the crisis.
"The ungrounded threats to Russia from the US and NATO over its Ukrainian policy are regarded by us as an unfriendly gesture and allow us to announce force majeure," the unnamed source is quoted as saying by the state-owned RIA Novosti news agency.
"We are ready to take this step as a response to Pentagon's statements about suspension of engagements between armies of Russia and the US," the source said.
In the latest version of the START treaty, which was originally agreed in 1991, the United States and Russia pledged to cap the number of deployed strategic nuclear warheads to 1,550 each and cut their numbers of strategic nuclear missile launchers in half by 2018.
The treaty allows each side to conduct 18 on-site inspections per year in the other country.