Homeland missile defense projects remain in Limbo.

• Author: Harper, Jon

* Uncertainty surrounds the future of homeland missile defense at a time of budget constraints and technology challenges.

Efforts to protect the United States from ballistic missile attacks are being driven by North Korea's pursuit of long-range rockets and concerns that Iran is moving in the same direction, U.S. officials have said. Pyongyang has already conducted three atomic bomb tests, and recently claimed that it tested an even more powerful hydrogen bomb. The Pentagon is worried that North Korean intercontinental ballistic missiles could potentially be armed with nuclear warheads.

"Those threats continue to put at risk the peace and security ... of the United States," Secretary of Defense Ash Carter said during a recent trip to South Korea.

The Defense Department is in the process of beefing up its missile shield by adding more ground-based interceptors to the existing site at Fort Greely, Alaska. Additional interceptors are located at Vandenberg Air Force Base, California. But the Pentagon has yet to endorse lawmakers' proposals for the creation of a third missile defense site in the eastern United States.

Under congressional prodding, the department has been conducting environmental impact studies of four potential basing areas: Fort Drum, New York; Fort Custer training center in Michigan; Camp Ravenna joint military training center in Ohio; and the SERE East [survival, evasion, resistance and escape] training area in Maine. That work is expected to wrap up in 2016, and the Missile Defense Agency has been tasked by Congress to select a preferred location in case policymakers decide to move forward with the project.

Having a site in the eastern United States would offer some operational advantages because it would buy time and space for intercepts, experts said.

It "allows for the opportunity of shoot-look-shoot," said retired Air Force Brig. Gen. Kenneth Todorov, former deputy director of the Missile Defense Agency, during a recent panel discussion at the Center for Strategic and International Studies. "It gives you a second shot opportunity should you have the means to determine that you ... didn't hit [the incoming missile] on the first try" after using the interceptors in Alaska.

But defense officials have balked at the expected price tag. The Congressional Budget Office estimated that the cost would exceed $3 billion, and Pentagon officials have argued that the money could be better spent on other projects.

"It comes at a...