The United States has activated its ground-based interceptor missile defense system amid concerns over a possible missile launch by North Korea, news reports said Tuesday.

An American defense official has confirmed a Washington Times report on Tuesday that the Pentagon had switched its multibillion-dollar missile defense system from test mode to operational, Reuters reported.

"It's good to be ready," the official was quoted as saying.

The Washington Times reported Tuesday that the Pentagon activated its missile defense system within the past two weeks and that US officials announced any long-range missile launch by North Korea would be considered a "provocative act."

An option being considered would be to shoot down the missile with responding interceptors, the Times report quoted a senior administration official as saying.

Two US Navy Aegis warships were patrolling near North Korea as part of the global missile defense and would be among the first sensors that would trigger the use of interceptors, the report said.

The United States has installed to date 11 ground-based missiles for its missile defense system - nine at Fort Greely, Alaska and two at Vandenberg Air Force Base in California, to intercept and destroy incoming long-range missiles in space.

(Xinhua News Agency June 21, 2006)