Washington ? Work on underground silos for missile interceptors will begin in Alaska on June 14, the first day the government will be freed from a 1972 treaty that bans major missile defenses, the head of the Pentagon’s Missile Defense Agency said Tuesday.

Withdrawal from the treaty also gives the U.S. military more freedom to explore the use of additional radars as part of a missile defense system, Lt. Gen. Ronald Kadish said in an Associated Press interview. For example, a ship-borne Aegis radar will be used in a July missile intercept test.

The timing of the actions suggests an urgency within the Bush administration to get moving on the missile defense system.

In January President Bush gave the required six-months notice of U.S. intent to withdraw from the Anti-Ballistic Missile treaty, despite strong objections by Russia and doubts among U.S. allies.

The radar test “was specifically prohibited by the treaty, so it’s never been done before,” said Kadish, a three-star Air Force general.

He answered questions in his office, which is adorned with models of military aircraft, including one of a modified Boeing 747 designed to shoot down missiles in flight with a laser.

The work in Alaska on underground silos for missile interceptors is an example of a project that would have collided with ABM restrictions. The plan is to build five missile interceptor silos and associated communications systems this summer so that by September 2004 the site, at Fort Greely near Fairbanks, could be available in an emergency.

The United States currently has no land-, sea- or space-based means of shooting down long-range missiles.

Kadish said that he has no doubt that the United States one day will be threatened with a missile attack.

“It’s only a matter of time, from my point of view, that we’ll be facing this threat, up close and personal, I’m afraid,” he said.