* US interceptors are now in Alaska, California
* Third site would boost defenses against Iran
* Fort Drum, New York, is said to be a potential site
By Jim Wolf
WASHINGTON, April 25 (Reuters) - Republicans who control the House of Representatives' Armed Services Committee called on Wednesday for studies on what could become a third missile-interceptor site in the United States, this one on the East Coast.
The plan would require the secretary of defense to conduct an environmental impact review by Dec. 31, 2013, on "possible locations on the East Coast of the United States for the deployment of a missile defense site."
U.S. forces currently deploy a combined total of 30 operational missile interceptors in silos in Fort Greely, Alaska, and Vandenberg Air Force Base in central California.
The three-stage interceptors are part of a layered shield against limited numbers of missiles that could be fired by a country like North Korea or Iran, some day potentially carrying a nuclear warhead.
The proposed step toward a third site is to be considered Thursday by the Armed Services subcommittee on strategic forces, an early stage of the crafting of the annual defense authorization bill that guides military policy.
The proposal was made public by Representative Howard McKeon, chairman of the full committee, and Representative Michael Turner, the subcommittee head. Such legislation is likely to be adopted by the full, Republican-controlled committee. It would have to be meshed with a companion defense authorization bill in the Democratic-controlled Senate, which has not yet put one together.
It was not immediately clear whether the Obama administration would support such steps toward an East Coast missile site.
The House Republicans' measure would require the Pentagon's Missile Defense Agency to develop a plan for the deployment of an East Coast site to be operational not later than the end of 2015.
Advocates of an East Coast site have said it would bolster the Boeing Co-managed ground-based shield against any intercontinental ballistic missiles that could be fired from Iran. One likely site is Fort Drum in northern New York state, according to experts.
"The committee is aware that a cost effective missile defense site located on the East Coast of the United States could have advantages for the defense of the United States from ballistic missiles launched from the Middle East," the bill said.
Baker Spring, a missile-defense expert at the Heritage Foundation think tank, said current U.S. capabilities for countering long-range missiles were geared chiefly toward North Korea, providing greater defense of the western United States than the east.