Iceland ? The United States, which long has provided Iceland with its only military force, has decided to withdraw most of its service members and all of its fighter jets and helicopters from the country later this year, the U.S. ambassador said Thursday.

Iceland’s government, which recently had offered to pay some of the cost of its defense to try to keep U.S. forces here, said it regretted the decision.

But Washington also said it would continue to honor its 1951 agreement with Iceland requiring the United States, under the auspices of NATO, to provide this country’s defense. U.S. and Icelandic officials will meet to discuss how that will be done.