Judge: 9-11 attack 1 incident, not 2.

Larry Silverstein's $7 billion 'two separate attacks not one' claim was shaken last week after a federal judge ruled that three of 20 insurers owe Silverstein money for only one attack on the World Trade Center.

Under the summary judgment, Royal Indemnity Company, Hartford Financial Services Group and St. Paul Companies are responsible for $112 million of a single $3.5 billion reimbursement.

Silverstein--who leased the WTC less than two months prior to the attacks-- contends that two separate plane crashes entitle him to double the $3.5 billion insurance coverage on each tower, allotting him $7 billion to rebuild on the site. The north tower of the WTC was struck by the first jet only 16 minutes before the second plane hit the south tower.

Making matters even more complicated, the insurers had only signed binder agreements pledging to provide coverage as the final documents hadn't yet been signed.

Herein lies the real dispute-Silverstein maintains that all of the WTC insurers were bound by a Travelers' insurance policy. The insurers, however, have asserted that they are bound by a more detailed document drafted by Willis Group Holdings. The Travelers' policy does not explicitly define "occurrence" while the Willis document covers all losses or damages "that are attributable directly or indirectly to one cause or to one series of similar causes." This wording--or lack thereof in the Travelers' policy--has become the thorny heart of the legal matter.

Marc Wolinsky, one of Silverstein's attorneys, did not return calls for comment on the summary judgment ruling.

The judge in the case ruled that under the terms of the insurance form used by three of the insurers the attacks were in fact one single occurrence.

"The ordinary businessman would have no doubt that when two hijacked planes hit the Twin Towers in a 16-minute period, the total destruction of the World Trade Center resulted from one series of similar causes," wrote federal judge John Martin.

The ruling allows five of the original 22 insurers of the WTC to pay Silverstein for only one event. It's expected that a string of trials will be held to determine if the remaining 17 insurers owe double the amount.

Swiss Re provided the lion's share of insurance coverage, and their chairman was naturally pleased with the ruling.

"It confirms what we've said all along. What happened on Sept. 11 was one occurrence. It points out the fiction in the Silverstein theory," said Jacques Dubois in last Thursday's New York Times.

A jury trial is set to begin Nov. 4.