Flying high above the sands of the Middle East en route from Ankara, Turkey, last Thursday afternoon, a State Department official presented his new and as yet unfamiliar boss, Edmund Muskie, with the draft of a statement to be made in a few hours to Southeast Asian leaders gathered here.

Muskie did not like it.

In the standard bureaucratic fuzz of Foggy Bottom, the planned remarks reassured Asia and the world that the United States would abide by its "security commitments."

The context, and the reason for restating the obvious, was the Vietnamese military incursion several days earlier across the border of Thailand, a U.S. ally.

"What does this mean, security commitments?" Muskie demanded in the office cabin of the secretary of state's specially fitted Air Force jet. "Does this mean we go to war -- or what?"

The longtime U.S. senator and former presidential candidate has a deep aversion, it seems, to ambiguous words that may be taken as serious promises. He demanded to know what actual resources were available from the United States to back up the flowing phrases of support for Thailand against the threats from the well-armed Vietnamese.

When Muskie was informed that an accelerated military aid program for Thailand was under discussion in Washington, but not decided, he balked completely. According to a participant in the airborne deliberations, Muskie declared that "I'm not going out there to mouth empty rhetoric," adding that "if there isn't any substance to this, I am not going to say the words."

The State Department officials, under Muskie's goading, began firing off urgent messages from the elaborate communications console of the aircraft to Washington.

In the capital, officials of State, Defense, the National Security Council, the Office of Management and Budget, the Agency for International Development and others had to be consulted about substance -- as opposed to words -- for Thailand. Money is short in government these days, even for a beleagured ally in a region where not long ago billions of dollars and the blood of Americans flowed freely.

After 12 hours of "screaming cables," as a member of State's Bureau of East Asian affairs referred to the messages, a modest but tangible program for Thailand was approved by Washington.

A classified cable approving expanded aid for Thailand reached Kuala Lumpur just minutes before Muskie's plane touched down from its 12-hour flight across the rim of Asia.

Four hours after landing, the secretary of state informed Thai Foreign Minister Siddhi Savetsila of the expedited military equipment and supplies, refugee aid and other assistance offered by the United States as a show of positive support in the face of the Vietnamese military challenge. Thailand earlier had requested help. Siddhi, who was an Air Force general before recently being tapped as a diplomat, understood the significance of the quick response.

"We really appreciate that the American government backed their commitment to our country, not by words only, but by action," the Thai foreign minister said in a press conference here today.

The story of the Thai aid program -- which may or may not make a difference amid the national and ideological clashes of this region -- tells something about the education of the State Department to its new and inexperienced boss.

"The people working around him don't know it yet, but it was a typical Muskie performance," said a long-time aide who has followed the veteran senator into the unfamiliar corridors of diplomacy.

The characteristic Muskie question, in this view, is "and then what." According to aides, he is unsatisfied to know in any given situation the probably effect of his next word or deed, but insists on thinking ahead to the step that must be taken in reaction, and the next after that.

He is a careful man who likes not only to look but to weigh, argue and analyze before he leaps, traits that bedeviled his chances as a presidential candidate because they often precluded reaching quick decisons. It is too early to know how these traits will fare in an administration that has been famous, until this point, for overnight reversals and instant policies in foreign affairs.

Muskie's method at this mission to the foreign ministers' meeting of the Association of Southeast Asian Nations (ASEAN) involved a minimum of sweeping declarations and a modest number of tangible promises and actions.

More than his other ports of call since becoming secretary of state seven weeks ago -- meeting of NATO allies at Brussels and Ankara, a meeting with Soviet Foreign Minister Andrei Gromyko at Vienna, the summit at Naples -- the trip to Southeast Asia revolved more around a new turn of events in which policy is malleable. In this case, Muskie was better able to exercise his preferences.

The Muskie-engineered U.S. response to the Vietnamese challenge at the Thai border was "very carefully calibrated," a senior State Department official said.

If the Vietnamese continue their incursions or even, as some reports suggest, seek to seal of Thai-Cambodian border where the trouble is, there will be new challenges ahead testing Thailand and its closest great power sponsor, the United States. These, too, said the official, are likely to be "carefully calibrated."

Muskie refused comment on the likely challenges in the region if the Vietnamese persist, except to say that emerging problems of feeding Cambodians across an embattled Thai-Cambodian border create "a potentially explosive situation." He refused to be drawn out about what the United States would do if new trouble erupts, saying that speculation would not be useful.

In fact, the evidence is that he has only begun to explore the contingencies and potential consequences.

By exploring too many situations in too much depth, and by challenging long-accepted practices, some State Department officials said, Muskie may be in danger of "reinventing the wheel" -- which means learning the hard way what others already know. There may be little time for that in a world in crisis.

Muskie, however, seems far from content with the diplomatic reality -- or unreality -- as he has found it. Within the reach of his power in the job, he appears determined to do things his way.