WASHINGTON - Japan may be getting set to pour hundreds of millions of dollars into plugging missile-defense gaps demonstrated by North Korea's July 4-5 test- firings, a Lockheed Martin Corp. executive said Wednesday.

Also being discussed is removing "barriers" to coordination with the United States to thwart missiles that could be tipped with chemical, biological or nuclear warheads, said Ed Butt, head of a Lockheed missile-defense division.

Bethesda, Maryland-based Lockheed Martin is the Pentagon's chief supplier. It heads one of two U.S.-led industry teams building a battle-management system as the nerve center of the multibillion-dollar shield involving systems on the ground, at sea and aloft.

"Over a period of five years, we're talking about a few hundred million dollars" in Japanese investments, potentially in command and control systems of its own, as well as in U.S. solutions, Butt said in a teleconference with reporters.

Lockheed is linking sensors, interceptors and other components to give military commanders a range of ways to cope with any missile attack. It would let them respond with everything from Patriot Advanced Capability-3 batteries to Aegis cruisers to ground-based interceptor missiles.

But when it fired short-, intermediate-and long-range missiles starting in July, North Korea demonstrated it was able to attack the emerging shield's "seams," Butt said.

"So for example, if all the systems in the Sea of Japan were focused on shots that may be heading for say South Korea ... you may miss intermediate launches going to Hawaii, or possibly something going into Japan," he said.

Butt said talks aimed at plugging such gaps had taken place last month and were scheduled to resume this month, involving US political and military officials. He said one issue was both sides' "reluctance" to share fully command and control systems for what he called "obvious military reasons."

"Those barriers are being toppled fairly quickly," Butt added.

Richard Lehner, a spokesman for the Pentagon's Missile Defense Agency, said he did not know who might attend any such meeting from his agency, or if anyone there had been invited.

Japan is working through issues tied to how far it may go in coordinating its missile defenses with the United States under its US-imposed pacifist constitution. It is due to spend more than US$1 billion in the coming year for on Patriot PAC-3 and Aegis sea-based missile defense.

Mike Trotsky, a Lockheed vice president, said the company had received or was about to receive another Japanese missile- related request. He withheld details citing Japanese wishes.

The Japanese request was made directly to former Defense Secretary Donald Rumsfeld and was approved in the last quarter of 2006, Trotsky added.