DETROIT (AP) Leaders in Michigan and Ontario say a system of "reverse inspections" could prevent Terrorists from crossing the U.S.-Canadian border and speed up delays that have been plaguing the crossings since the Sept. 11 attacks.

U.S. Sen. Carl Levin and Remo Mancini, corporate vice president of the Canadian Transit Company, said the move is needed for the safety of both countries and to streamline international trade commerce between the two countries.

"If you want to protect your bridges and tunnels from explosives than you do it before people cross them not after," Levin (D-Mich.) said. "It"s a no-brainer."

Levin said he does not see any major problems with establishing the new system, but said he"s yet to receive an answer from U.S. Customs officials and doesn"t understand what"s taking so long.

On Friday, Levin and fellow Democratic Michigan Sen. Debbie Stabenow sent a letter to the commissioner of the U.S. Customs Service urging the implementation of the system.

Levin said that if he doesn"t receive an answer by Jan. 18, he will convene a congressional committee hearing and call the commissioner to testify.

"This is a matter of principle," he said. "Once we get an answer, there are a number of logistical issues, but I think we can solve them."

Under a "reverse inspection" system, United States and Canadian customs officials would set up stations on opposite sides of the border.

Forms of the system are found at a few Canadian airports and at the English Channel tunnel, Mancini said.

Jim Mitchie, a spokesman for U.S. Customs in Washington, said customs officials are aware of Levin"s letter and that a response is forthcoming.

Mitchie said that reverse inspections are one of a number of changes that American and Canadian officials are considering to improve safety and efficiency. But he said there"s no time frame for making a decision on its implementation.

A plan commissioned by Canadian Transit includes the creation of an "International Zone" that would span both sides of the border. There would be separate traffic lanes for frequent crossers like those in the Nexus program and the Just in Time delivery service, Mancini said.

A short-term plan could be implemented in as little as 90 days and a long-term plan, which would include the construction of new buildings and the acquisition of new property, could be up and running in 20 months, he said.

The Ambassador Bridge, which links Detroit and Windsor, Ontario, is the busiest U.S.-Canada entry point with more than 12 million vehicles crossing a year.

There are three other major bridge crossings in Michigan including the Detroit-Windsor Tunnel in Detroit and bridges in Port Huron and Sault Ste. Marie.

Smaller crossings include ferries at Marine City and Algonac in St. Clair County.

In the first days following the Sept. 11 attacks, heightened security at Michigan"s border crossings caused delays of 12 to 15 hours for those waiting to cross. National Guard troops have been helping to staff the border and move vehicles across the border.