London — Has Britain, the firmest United States ally abroad, become a weaker member of NATO because of its heavy losses and continuing commitment in the Falkland Islands?
A number of politicians and strategists here and in the US worry that the loss of two destroyers, two frigates, assorted aircraft and helicopters, and almost 300 men in the Falklands campaign has pulled British defense spending out of shape.
Now the Conservative government of Margaret Thatcher has tried to meet these concerns by arguing that the lesson of the Falklands is not alarming for NATO but reassuring.
Defense Secretary Michael Heseltine conceded July 6 that the remote, sparsely populated Falklands did not seem to be immediately related to Europe. Yet, supported by the defense estimates released for 1983-84, Mr. Heseltine went on to make two main arguments:
* Any assessment of Western defenses as a whole must include enhanced British will and defense capacities as demonstrated in the victory against Argentina.
* British forces learned a number of specific lessons from the Falklands campaign and are now translating them into new weapons and techniques.
The new defense estimates put the cost of the Falklands campaign at (STR)318 million ($485 million) for 1982-83 and (STR)624 million ($950 million) in 1983- 84. However, the cost of replacing ships and planes is spread out over a number of years.
A House of Commons defense committee estimates it will cost up to (STR)200 million a year to maintain the British garrison at Port Stanley. Over 10 years, costs of roads, the new long-runway airport, and other items would reach (STR)5 billion.
The defense estimates, the first the government has released since the June election, confirm the Conservative's priority on pro-US, pro-NATO defense policies.
Mrs. Thatcher plans to deploy cruise missiles at the US Air Force base at Greenham Common near London by the end of this year, unless the Soviets agree to zero deployment on both sides (thought almost certainly impossible at this stage). She also appears determined to spend up to (STR)10 billion on US Trident missiles for British-built nuclear submarines.
The Labour Party and others here argue Britain cannot afford to spend so much on defense. Defense is the second largest item in the British budget (behind social welfare).
Meanwhile, the British seek to put the lessons they learned in the Falklands in NATO, anti-Soviet terms. They argue that the Falklands showed that ''successful deterrence rests crucially on the perceptions of a potential enemy.''
The Argentines miscalculated British resolve. Therefore, Mr. Heseltine insists, it is vital that Moscow not misunderstand NATO's own commitment to keep its defenses high, reject one-sided disarmament, and deploy cruise missiles unless agreement is reached at the Geneva talks.