WASHINGTON - The United States and Romania have agreed on a site to install missile defense interceptors as part of a planned US shield over Europe.

Related readings:  Pakistan test fires nuclear capable cruise missile  Russia successfully test-launches Sineva ICBM  US stages 'most challenging' missile-defense test  NATO, Russia to resume missile defense drills

US Undersecretary of State Ellen Tauscher and Romanian President Traian Basescu were announcing the decision Tuesday in Bucharest to build the interceptor site at the Daveselu air base near the Bulgarian border. Romania already had agreed to host the interceptors, but the location had not been announced.

In an interview with The Associated Press ahead of the announcement, Tauscher said the interceptors would be operational as planned by 2015.

The Romanian site is part two of a four-part plan that the Obama administration outlined in 2009, when it shelved a Bush administration plan to use long-range interceptors based in Poland to counter a threat from Iran and Democratic People's Republic of Korea (DPRK). That plan was opposed by Russia, which worried that the system could target Russian warheads or undermine the Kremlin's deterrence strategy.

The Obama administration has said its plan - designed to counter the threat of short-to-medium range missiles - would be more effective and able to counter a threat from Iran earlier. But critics have said that the new plan caved in to Russian demands and have doubted whether the administration could build an effective shield in the timetable promised.

"We continue to do what we said we were going to do when it comes to missile defense," Tauscher said. "We are right on track, right on time."

The administration's plan calls for placing land- and sea-based radars and interceptors in several European locations over the next decade and upgrading them over time. As the first part of the plan, the United States in March deployed to the Mediterranean the USS Monterey, a ship equipped to detect and shoot down missiles.

Each phase of the four part plan calls for a more sophisticated and capable interceptor, culminating at the end of the decade with the deployment in Poland of more advanced interceptors that still are in development.

The administration has said the placements are designed to ensure coverage of all of Europe. Daveselu air base is about 200 kilometers (125 miles) southwest of Bucharest.