At his March 4 staff meeting, President Reagan exposed the SALT policy vacuum when, noting a State Department statement in the morning newspapers that the United States would adhere to SALT I and SALT II, he asked: Who in the world at State is saying that?

"Who in the world" happened to be Secretary of State Alexander Haig himself. Thus, after two months in office Reagan's question reveals not only an information gap on SALT between him and his senior Cabinet officer but also administration delay in deciding what to do about arms control.

Reagan has not yet placed the tricky SALT question before his National Security Council. It has not been the subject of a single top-level discussion, despite its critical effect on U.S.-Soviet and U.S.-European policy. No effort has been made to shape the president's rearmament program, including nuclear weaponry, to conform to a SALT policy not yet determined.

All of Reagan's senior aides in the Oval Office that morning, were aware that the "who in the world" at the State Department was Al Haig. But not Ronald Reagan.

That morning's news account quoted the State Department that the United States was "adhearing for now" to both SALT packs -- Richard Nixon's expired SALT I and Jimmy Carter's unratified SALT II -- if the Soviets did likewise. Haig ordered that policy statement issued in intentionally dramatic form (reporters were telephoned about it at home) to drive home his repudiation of Secretary of the Navy John Lehman. A day earlier, Lehman declared that as far as he was concerned, the two pacts were null and void in terms of limiting U.S. rearmament.

Indeed, Lehaman had quietly halted the conversion of older-type Polaris submarines to boats incapable of firing nuclear weapons, a downgrading required under the limits imposed by the lapsed SALT I agreement. Lehman, deputy arms control director in the Ford administration, has been a sharp critic of the treaties. Besides, judging from everything Reagan said during the presidential campaign about the inequitable SALT process, Lehman had reason to think he was carrying out administration policy.

The president clearly had not been briefed either on Lehman's decision to treat SALT I as a dead letter or on Haig's decision to stick to both pacts so long as the Soviets do. The breakdown in communications reflects Reagan's own inclinations.

White House staffers claim that, unlike Richard Nixon, who hated the perplexities of domestic policy, Reagan is fascinated by the nuances of building and enacting his economic program and less interested in national security complexities.

Reagan also is committed to "Cabinet government," which encourages his Cabinet members to stretch their powers as far as they can get away with. "The question," one aide told us, "is when does Al Haig or Cap Weinberger leave off and Ronald Reagan take over? There is no answer to that yet."

The failure of the Reagan system to devise an administration-wide strategy on SALT is adding to the chronic anxiety of U.S. allies in Europe, where domestic left-wing political pressure against nuclear weapons is growing. Haig's swift, harsh reprimand to Lehman was intended to supress this European political agitation.

But only Reagan himself can do that, and in the end he may decide not to. He may decide to take the heat from the Europeans, abandoning SALT until, far in the future, new negotiations result in a different kind of treaty.

It is not only John Lehman who strongly advocates that course. Secret administration studies nearing completion have identified several "quick fixes" to make the now vulnerable U.S. landbased missile system safe from a possible Soviet first-strike. But these "fixes" would violate SALT II.

One indication that Reagan may well choose that course, despite Western Europe's anguish, is the continuing battle inside the administration over alleged Soviet violations of SALT I. Instead of publicizing examples documented by U.S. intelligence, they may be shelved. The reason: It would be embarrassing to accuse the Kremlin of violating the SALT treaties if Reagan intends to declare both pacts null and void.

The issue is ignored by the president's national security apparatus. Reagan has chaired NSC meetings on a dozen big issues, such as putting American troops into the Middle East or granting new military aid to Pakistan. The SALT issue is still disembodied, with the president himself surprised at decisions being made in his name.