"It's an activity that has been evolving over time and is important for the protection of the American people," Rumsfeld told reporters after being briefed about the interceptor missile activities here. "It is an activity that with each passing month has become more capable."

The U.S. missile defense system is still limited and needs more testing, but it is important to have when North Korea and Iran are demonstrating their desire and capability to have nuclear programs, and terrorist groups are using rockets to attack civilians, Rumsfeld said. He said he has been involved in the missile defense program since its inception and has seen it go through much debate and change before arriving at its current state.

"I've seen the thing calm down to the point where it's now national policy, in law, that the United States develop a capability to defend itself against limited types of threats," he said.

Rumsfeld specifically talked about the threat coming from North Korea, saying it wasn't a military threat, but one of proliferation. North Korea's recent test launch of several missiles clearly demonstrates the country's determination to develop a nuclear program, he said, but Pyongyang is probably mostly interested in selling the missiles to other countries.

"I think the real threat that North Korea poses in the immediate future is more one of proliferation than a danger to South Korea," he said.

After touring the missile facilities, Rumsfeld met with Russian Defense Minister Sergei Ivanov in Fairbanks, Alaska. The two discussed the U.S. missile defense system and how it affects Russia, as well as regional and security issues. At a news conference following the meeting, Ivanov noted that the U.S.-Russia relationship is important to the global security and political climate.

"Irrespective of the issues which we discussed, we always hope that there will be transparency and predictability, as well as the mutual respect of our governments' interests," he said through a translator.

At the news conference, Rumsfeld talked about the U.S. plans to put conventional warheads on intercontinental missiles for possible use against threats. The capability would be good for any government to have in the case of an unforeseen threat from a weapon of mass destruction or terrorist group, he said, and would be far less destructive than a nuclear weapon.

"If either of our countries or our friends and allies were threatened in the future with a weapon of mass destruction or a capability that is that lethal, I think any president would like to have available a conventional weapon that could attack that target swiftly and accurately and precisely," he said.

Rumsfeld emphasized that whatever was done in this area would be fully transparent between the U.S. and Russia, and appropriate communications links would be developed.

After the meeting, Rumsfeld and Ivanov attended a dedication ceremony for a memorial to U.S.-Soviet military cooperation during World War II.

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