WASHINGTON?The Pentagon has proposed a plan to reduce the number and frequency of round-the-clock combat air patrols flown over American cities since the Sept. 11 terrorist attacks, a spokeswoman said Monday.

Pentagon spokeswoman Victoria Clarke said the agency would use “intermittent combat air patrols on an ad hoc basis,” and put fighter jets at various military bases on “strip alerts,” allowing a 15-minute notice for combat duty.

The spokeswoman said she did not know of a definite date for implementing the plan.

New York’s Democratic senators, Charles Schumer and Hillary Rodham Clinton, questioned the decision to cut the flights.

In January, the Air Force’s top civilian official said the patrols were putting too much strain on the Air Force.

The post-Sept. 11 combat air patrols were the first of their kind over the United States since the Cuban missile crisis in 1962.