MINNEAPOLIS — Northwest Airlines Corp. flight attendants rejected a wage-cutting contract yesterday and warned of random, unannounced strikes as early as mid-August.

Northwest said a strike — which could spook travelers and hinder the airline's bankruptcy restructuring — would be illegal and that it would seek a court order to block one. The union pledged to give 15 days' notice before any strike, a move it had not made as of last night.

Northwest has sought $1.4 billion in annual labor savings as it reorganizes in bankruptcy court. Flight attendants are the last union at Northwest, the nation's fifth-largest carrier by the standard industry measure, without a wage-cutting contract. But the airline's deals with pilots and ground workers don't take effect until there's a new contract for flight attendants, too.

Northwest moved quickly to impose a new contract after 55 percent of flight attendants voted down the tentative agreement yesterday. Flight attendants had rejected a slightly different tentative agreement in June.

"This decision is an example of the flight attendants' determination not to watch their livelihoods be squandered by management," said Corey Caldwell, a spokeswoman for the Association of Flight Attendants.

Before yesterday, Northwest already had permission from a bankruptcy judge to impose the terms of an earlier tentative agreement that 80 percent of flight attendants rejected in June. Northwest has been seeking worker pay cuts since 2003, and yesterday it said time was up.

"Notwithstanding the results of the flight attendants' contract vote, Northwest must continue to move forward with its restructuring efforts," Mike Becker, senior vice president of human resources and labor relations, said in a statement.

Its new agreements with pilots and ground workers cannot take effect until it has a new contract with flight attendants, too — either one that workers approve, or one the company imposes on them.

The union asked a bankruptcy judge to limit Northwest to imposing the terms rejected yesterday, rather than the terms rejected in June. Both would save Northwest $195 million a year, and both include pay cuts of roughly 21 percent. The union said the reduction amounted to 40 percent once healthcare costs and other givebacks were factored in.

"People are angry," said Mollie Reiley, interim president of the union's Northwest branch, which had recommended passage of the tentative agreement.

"This is about justice. When you're making 28, 29, 30 thousand dollars a year and you're being asked to take close to a 40 percent cut in wages, benefits, overrides, et cetera, people can't afford it. They're going to lose their homes. They won't be able to afford to stay. I think a lot of our people just said, enough's enough."

The union said the imposition of those terms would be its trigger for what it calls CHAOS, for Create Havoc Around Our System. The union has described the tactic as using random, unannounced strikes on certain flights or certain gates.

It's a way to disrupt a carrier without gambling on shutting down the entire airline — a gamble flight attendants might lose.

The union has said it has a list of flight attendants who have volunteered to conduct limited strikes against the airline. But Bradley Bartholomew of The Newfoundland Group, which does airline labor consulting, questioned whether job actions by the union would do anything more than start a test case in the courts.