WASHINGTON, Jan 31 (Reuters) - The U.S. Defense Department said on Friday it would conduct environmental impact studies for four possible missile defense sites in the eastern United States but stressed it had not yet decided to proceed with construction.
Congress, worried about Iran's efforts to develop intercontinental ballistic missiles, is urging the Pentagon to commit to an East Coast site. Defense officials say current interceptors on the West Coast can defend the country against possible missile attacks, and an extra interceptor site would add enormous costs to a military budget already under pressure.
Still, Pentagon officials are proceeding with the environmental impact study required under a directive in the 2013 defense authorization bill. In a statement issued Friday, the department said it would take about two years to complete a comprehensive environmental impact study, which will look at potential impacts to land use, water resources, air quality, transportation, socioeconomics and other factors.
The four sites are Fort Drum, New York; SERE Training Area at Naval Air Station, Portsmouth, Maine; Camp Ravenna Joint Training Center in Ohio; and Fort Custer Training Center in Michigan.
A fifth possible site - Camp Ethan Allen Training Site in Vermont that had been identified in September - was dropped from the list of sites to be studied further. It was not immediately clear why it was dropped.
U.S. lawmakers, worried about the ability of West Coast missile defense sites to protect against all possible missile threats, have pressed the Pentagon to consider adding sites in the eastern half of the country.
The 2013 defense authorization law required U.S. officials to identify three possible interceptor sites, including at least two on the East Coast.
Senator Kelly Ayotte, a Republican from New Hampshire, said selection of the four sites marked an important step forward, but urged the Obama administration to speed up work on the environmental impact statement (EIS), given Iran's reported continued work to develop long-range missiles.
"In light of the fact that Iran may have an intercontinental ballistic missile (ICBM) capable of striking the continental United States as early as next year, I call on the administration to expedite the EIS and move without delay to build a missile defense interceptor site on the east coast of the United States," she said in a statement.
Riki Ellison with the nonprofit Missile Defense Advocacy Alliance, said the United States faced other more pressing missile defense needs than creation of a new interceptor site, including a redesign of the part of the rocket that is used to hit enemy missiles and destroy them on impact.
The Pentagon's chief weapons tester recommended work on a new "kill vehicle" in a report this week.
Kingston Reif, with the nonprofit Center for Arms Control and Non-Proliferation, noted that the Congressional Budget Office had estimated that it would cost about $3.5 billion over the next five years to build a third interceptor site.
"This is money the Pentagon does not have and does not want to use for this purpose," he said.
(Reporting by Andrea Shalal-Esa; Editing by Ken Wills)