The U.S. plan to defend Europe from a rapidly increasing ballistic missile threat will reach a milestone next week with the first deployment of missile defense technology, a senior Defense Department official said yesterday.

"The ballistic missile threat is real, and it's now," said John F. Plumb, the Pentagon's principal director for nuclear and missile defense policy, adding that the phased, adaptive approach to European missile defense is a capability designed to defend against that threat.

The USS Monterey - equipped with systems to detect, track, engage and destroy ballistic missiles in flight - will deploy next week from its home port of Norfolk, Va., for a six-month tour in the U.S. European Command area of responsibility, Plumb said.

The ship will participate in missile defense exercises and help to lay the foundation for future deployments, Plumb said, in "the first demonstration of our commitment to this ... in a long series of deployments that will follow."

President Barack Obama approved the phased, adaptive approach to European ballistic missile defense in 2009, and the NATO alliance agreed to the plan at its November 2010 summit in Lisbon, Portugal.

The approach will begin with existing technology and add more sophisticated systems now in development to build sea- and land-based missile defense systems in Europe throughout the rest of this decade, Plumb said.

"The first phase ... involves ships, because we have sea-based missile defense capabilities now, as well as forward-based radar that can provide information to those ships," he said.

The second phase will begin in 2015, he said, with the deployment of a land-based interceptor site in Romania. The interceptor, the Standard Missile-3 IB, or SM-3 IB, is in development now, Plumb said.

"That will be the first land-based deployment of this type of interceptor, and that will start to provide greater coverage for Europe," he said.

The SM-3 IA already is deployed on ships around the world, he said, and two other variants of the interceptor, the IIA and IIB, are scheduled to be in place as part of phases 3 and 4 by 2020. Plumb said each version of the interceptor will defend against missiles of greater ranges and speeds.

The ballistic missile threat to Europe from the Middle East, particularly Iran, is a driving force behind the phased, adaptive approach, he said.

"[Iran] continues to pursue more and greater capabilities," he said. "We need to have a way not only to deter them from using them, but also if deterrence fails to be able to intercept their missiles."

While the phased, adaptive approach is currently under U.S. European Command's authority, Plumb said, NATO agreed at the Lisbon summit to establish command-and-control systems allowing the alliance to take the lead in ballistic missile defense on the European continent.

"Europe is a big place," he said. "The more you can cooperate, and the more assets other nations can contribute, the better the system can function."

Those contributions may take the form of sensors, interceptors or land for sites, he said.

"The assets we're deploying ... would be the U.S. national contribution to the missile defense of Europe," Plumb said. "As with any other NATO mission, individual nations voluntarily contribute assets, and [all] would work under a NATO command structure."