Northwest Airlines is slashing jobs and flight schedules because the conflict with Iraq has put people off travelling.
Northwest is cutting back on flights
The world's fourth biggest airline said 4,900 jobs would go and flights would be cut by 12%.
It blamed the action on a drop in passenger demand because of the threat, and now the start, of hostilities with Iraq.
And it warned that it might have to take further action depending on how the war unfolds.
For the moment, approximately 20 planes will be taken out of service with the reduction in flights affecting North American, Asia-Pacific and European routes.
"We must take this measure in response to the reduction in demand due to the war with Iraq," said chief executive Richard Anderson.
Since the US-led attacks in the Gulf began, airlines have been queuing up to announce cuts.
On Thursday, the world's biggest airline, American Airlines, warned that it would have to cut its flights because of a drop in demand.
The chief executive told staff that, whatever happened, the airline would be affected by the war.
And Air Canada said it was reducing its workforce of about 40,000 by 3,600, saying the war underlined its need to cut labour costs.
Continental Airlines of the US and Australia's Qantas have also announced cuts in recent days.
The world's major airlines - particularly the ones that fly transatlantic routes - have suffered from the drop in demand for air travel because of the September 11 terrorist attacks and the world economic slowdown.
Several US carriers have had to go into bankruptcy protection and the industry as a whole is now facing a third year of heavy losses.