Almost six months after President Carter announced his policy to curtail the flow of American weapons abroad the bureaucracy is still struggling over how (a) define it and (b) execute it.

As one high-ranking official quipped, putting the President's policy into effect is like "trying to turn around a supertanker."

Last May 19 the President said the United States would not be "the first supplier to introduce into a region newly developed, advanced weapons systems which could create a new or significantly higher combat capability."

Notwithstanding the 5 1/2 months and three single-spaced pages of definition which have accrued to the administration's arms policy, no satisfactory way of to determine what is "an advanced weapons system" or a higher combat capability" has yet been found.

Carter's policy "has made a difference in semantics, but no differnce on practice," said Sen. Thomas F. Eagleton (D-Mo.), one of the harshest congressional critics of Carter's performance on his arms pledges. "Since May 19, I've seen no evidence of any restraint in arms sales."

Eagleton has at least a point. Whatever the administration has done since Carter announced his arms policy on May 19, it has not slowed the stampede of American weapons headed overseas.

Last month, the Library of Congress' Congressional Research Service reported that in the first four months after Carter enunciated the policy, the administration transmitted to Congress 45 arms sales notifications, involving 18 countries and more than $4.1 billion.

In fact, fiscal year 1977 - over which Carter presided for eight months - will reverse a two-year downward trend in total U.S. arms sales. Sales reached a peak of $10.6 billion 1974, and declined to $8.7 billion in 1976.

The figure for 1977, calculated on the same basic as previous years' totals, is estimated at $9.9 billion, an increase of 13 per cent over 1976. A recent change in accounting procedures will raise the 1977 figure to $11.3 billion, the highest total in history.

While congressional sources cononce again that they are by far the cede the accounting change is justifiable, they note it will dilute the impact of the centerpiece of Carter's policy, a pledge to reduce 1978 sales below the 1977 figure.

The change "gives them a higher figure to play around with in 1978," said one source.

Administration officials insist it will take 12 to 18 months for the effects of Carter's policy to show themselves. Most of the deals that will be concluded during that time, they say, will have deep roots that stretch back through years of discussions by previous administrations with purchasing nations.

"It's fair to say that it is a slow process, turning it around," said Ed Feingold, deputy director of the Arms Control and Disarmament Agency. "These thins have long tails, and relations between the U.S. and many of these states are affected by arms sales . . . It's really too early to know."

Lucy Wilson Benson, under secretary of state for security assistance and chairman of the interagency arms export control board, pointed out three requests Carter has turned down as evidence the administration is serious about controlling arms sales.

They include a request by Iran for the F-18L, a fighter not produced for any U.S. forces, one by Pakistan to purchase A-7 attack planes, and one by Israel to co-produce with Ecuador Kfir jets fitted with U.S. engines - a proposal that would have expanded the world's arms manufacturing base.

Critics point to Carter's recent decision to sell seven airborne radar and battle control systems to Iran for $1.2 billion as a move that makes a mockery of the policy.

The system, known as AWACS, seems to be an example of what Carter said he was trying to avoid. It is the most advanced weapon of its kind in the world, and is being introduced to a region where nothing remotely like it exists.

"AWACS does great violence to the President's May 19 statement," said Eagleton.

As the AWACS disput suggests, what the arms control policy is really all about is the Middle East.

In his May 19 statement, Carter specifically exempted the NATO allies. Australia, New Zealand, and Japan from pledge that the dollar volume of arms sales in fiscal 1977 would constitute a ceiling for arms sales in 1978, the fiscal year that began Oct. 1.

The ceiling applies to the arms sold to other nations last year. According to the most recent Defense Department figures, which include $8.7 billion of the estimated $9.9 billion of 1977 sales, just over $1.0 billion went to NATO and the three other allies. Of the rest, $5.9 billion, or 76.6 per cent, went to Israel, Iran, or Saudi Arabia.

A recent study by an independent research organization found that between 1974 and [WORD ILLEGIBLE], 65 per cent of U.S. arms sold abroad went to one of those three nations.

"What we do with those countries is everything," said ACDA deputy director Richard Wilcox.

Requests by the Middle Eastern governments for new shipments of arms during the current year are expected to test the mettle of Carter's commitment to reducing arms sales before the grace period the administration wants has expired.

Iran has asked for 160 F-16 fighters to complement the 140 F-16s it is currently receiving. Saudi Arabia has asked for F-15 jets to replace its aging fighter force. The battle over AWACS has left Congress with decidedly negative feelings about future sales to the Arabs, but officials say there are compelling reasons for approving at least the Saudi sale.

The most difficult testing ground for the new arms policy is Israel. Although Carter vowed on May 19 to "honor our historic responibilities to assure the security's of Israel, it is not one of the nations exempted from the ceiling.

Israel's "approach, out of some understandable desperation, is to keep upping the ante," said Priscilla Clapp, a top aide to leslie Gelb, head of the State Departments politico-military affairs bureau, which serves as Undersecretary Benson's staff.

Clapp said Israel is seeking a commitment from the administration for a continued flow of arms for 10 years or so into the future. The Washington Post reported last week that Israeli Defense Minister Ezir Weizman is expected to come to Washington soon with an arms shopping list described by one official as "staggering."

The Middle East aside, officials point to two built-in obstacles to the success of any policy that seeks to limit arms sales.

One is the impact of arms sales on the domestic economy. The arms business is big business; most of those $9.9 billion of sales last year represent money in someone's paycheck or profits for some corporation.

When Carter canceled the B-1 bomber program, Rockwell International said the decision cost 25,000 jobs. When supporters of the McDonnell Douglas Northrop F-18 aruged unsuccessfully for its purchase by the Navy, they said as many as 70,000 jobs were at stake.

Domestic economic considerations "in particular instances, are taken "in particular instances, are taken into account," said Clapp. "It wouldn't be fair not to."

On the other hand, she said, there is a backlog of $31.8 billion in orders not yet delivered that can help cushion the blow of a slowdown in sales.

The other obstacle is the group of nations outside the United States which can fill any gap in the world-wide flow of weapons that Carter's policy might create.

The United States now sells about 50 per cent of the world's arms, said Benson. "It's fair to say that we could contemplate, with some equanimity, the loss of some sales to another country," she said.

"But clearly, it would be difficult" if other suppliers rush in to the world's arms market just as the United States is trying to pull out. "Well's just have to wait and see."

At bottom, the question the policy poses is the tradeoff between what Carter views as the dubious morality of international arms sales, on one hand, and the political leverage the sales provide, on the other.

Under the two previous administrations, arms were systematically used as a prime means of obtaining leverage. Nations like Brazil, South Korea, Indonesia, and others were supplied with arms, and expected in return to look out for U.S. interests in their areas of the world.

Carter has not abandoned that policy. His administration has expressed a willingness to talk about selling arms to several nations in Africa - Somalia, Upper Volta, Mali - that are not now U.W. arms customers, but where the United States is interested in obtaining a foothold.

There is no easy replacement for arms in the contest for international leverage. The most obvious choices, food aid and economic aid, are impractical, officials say, because Congress regularly refuses to approve them without attaching strings unacceptable to either the United States or the receiving nation.

Administration officials consequently hedge their bets when talking about what they expect the policy to achieve. ACDA's Wilcox, for example, said Carter's May 19 statement was "partly an enthusiastic dive into a whole new area, and may have been a bit extreme . . .

"If you don't set high goals, you don't accomplish a thing," he said. "I am personally convinced that there has been a change in philosophy, that there will be less sales next year."

hen he adds, "But it is unfortunate that people will think the policy failed if we don't meet that [ceiling] goal."

Or State's Wilson: "I think al that one should conclude from the policy is that this administration recognizes the importance of arms as a foreign policy instrument. The perfect world has not arrived, but this administration is willing and anxious to reduce their importance - not to eliminate it - but to reduce it as a foreign policy goal.

"It's an experiment. If we can do it, it'd be super. On the other hand, one has to be realistic. It can't be done overnight."