By conventional standards, Michael Pillsbury's government career seems a failure. He was fired from a senate committee staff, passed over for a job early in President Reagan's administration, and, most recently, fired from the Defense Department. In nine years in Washington, he has never held a high-visibility post.

But in the murky world of Washington's sub-Cabinet struggles, Pillsbury is an acknowledged master of political machination. Most of his failures were preceded -- brought on, according to his friends -- by the kind of policy victories that incur powerful enemies for their engineers.

Theoretically, several hundred officials inhabit the exclusive substratum of Washington where major national security decisions are made. In practice, however, a band of no more than 20 individuals at any given time can be described as real players on key national security issues.

The sub-Cabinet level has become particularly important during the Reagan administration, as the Iran-contra scandal demonstrates: Marine Lt. Col. Oliver L. North is only the clearest emblem of the freedom of maneuver accorded to sub-Cabinet-level officials.

To push a policy, these operatives must have knowledge and imagination. To be heard, they have to know the levers of authority in Washington, and cement alliances within the administration and on the Hill. And to succeed, they have to take risks, and occasionally play dirty.

Even Pillsbury's detractors credit him as a strategic thinker, one describing him as a "brilliant" analyst whose proposals have been "far ahead of their time." But what makes him more than an average player is his willingness to push unpopular ideas, to "rock the boat," as one of his critics put it.

A Stanford graduate who got his doctorate from Columbia in Chinese studies and who speaks Mandarin, Pillsbury began his career as an analyst at the Rand Corp. There, in 1973, he developed the idea that the United States should establish a military relationship with communist China to balance the expansion of Soviet power.

The theme sounded heretical to most Americans -- especially so, one would have thought, to the man to whom Pillsbury chose to send an article he wrote on the subject. Ronald Reagan, the ex-governor of California, was perceived as a doctrinaire rightist completely committed to Taiwan.

But in a 1976 handwritten letter to Pillsbury, Reagan endorsed the idea, writing, "I am convinced we must strengthen this relationship with China to maintain a balance of power with Russia." And once Reagan was elected president, Pillsbury's thesis became U.S. policy.

Pillsbury came to Washington in 1978 to join the staff of the Senate Budget Committee, but was fired when he ran afoul of former Senate majority leader Mike Mansfield, then U.S. ambassador to Japan, for suggesting that Japan should be made to pull its military weight in the alliance. Two years later he broke into the executive branch as acting director of the U.S. Arms Control and Disarmament Agency on Reagan's transition team. Although he reportedly hoped to win a permanent job there, he was abruptly dismissed amid uncertainty over the direction the agency should take. But he surfaced again as assistant undersecretary of defense for policy planning.

That he managed to bounce back after each blow is largely due to the strong political support he enjoys among conservative senators. His ties to Sen. Orrin G. Hatch (R-Utah) have been described by a Pillsbury critic as "a father-son relationship." Other conservative senators who support him include Jesse Helms (R-S.C.), Gordon J. Humphrey (R-N.H.) and Chic Hecht (R-Nev.). Today he advises the four on foreign policy and national security issues.

Pillsbury's resilience, an air of intellectual abrasiveness and the illustrious family name -- he is related to the merchant-millionaire Pillsburys of Minneapolis -- combine to make him controversial. A number of prominent legislators seem almost mesmerized by his knowledge. Hatch, for example, believes that Pillsbury's "enemies" in the Pentagon high echelon include people "who are intimidated by his intellectual brilliance and those who are his equals but can't stand competition."

Pillsbury's critics, however, see him as an ambitious manipulator constantly seeking, through the media, to expand his influence. According to this view, he is not a real conservative, but has aligned himself with conservatives to advance his career.

Pillsbury was fired from the Defense Department last spring for allegedly leaking to the press information about the U.S. plan to provide Stinger missiles to anti-Marxist rebels in Angola, a policy he is widely credited with having pushed through the bureaucracy. He denies the leak, and friends say his firing was explained by his earlier success in internal Pentagon struggles.

One such struggle was Pillsbury's proposal in 1985 that the United States establish a military relationship with India. As the world's largest nonaligned country, he argued, India was "a neglected national security problem" exacerbated by the United States' strong ties to Pakistan, India's arch-enemy. The United States, argued Pillsbury, must seek to reduce India's dependence on the Soviet Union, which has been India's main foreign arms supplier for years.

Key Pentagon officials favored the idea in principle, especially Fred C. Ikle, undersecretary for policy. But Pillsbury encountered strong opposition when he proposed to bolster the overture by permitting sales to India of several hi-tech military items.

For Steven D. Bryen, deputy undersecretary for trade security policy, the more important goal was to choke off technological transfers to Russia. Another player, Assistant Secretary of Defense for International Security Affairs Richard L. Armitage, was concerned for his turf, and made it clear during a key meeting that he resented Pillsbury's initiative. "Armitage screamed, 'Just because he speaks Chinese it doesn't mean he should get mixed up in everything,' " said Pillsbury. The proposal also received a cool response from the Central Intelligence Agency and the Joint Chiefs of Staff.

Although he had some support in the State and Commerce departments and in the Senate, Pillsbury feared the bureaucracy's way of killing any such initiative: to call for more study. Hoping for a clear decision, he staged a "court" hearing in Ikle's office days before Ikle's planned visit to India in May 1985.

With more than 20 persons present in Ikle's large office, Pillsbury argued the case like a trial lawyer. He had mastered technical details about the items sought by India, assembled signed intelligence memos for each issue, and studied lists of countries to which the items had already been released by the Pentagon, showing that some items had been approved for shipments to a communist country.

After a three-hour show, Ikle sided with Pillsbury. Bryen later conceded Pillsbury's persuasiveness, saying he "played a provocative role in the process -- otherwise the thing would not have moved anywhere."

But Pillsbury's victory was costly, he believes, and "generated bitterness" against him.

And he went on with his "provocative" behavior. Humphrey said that Vice Adm. John M. Poindexter, then national security adviser, became annoyed with Pillsbury for "bringing to bear pressure on the White House to improve the quality of weaponry for {anti-Soviet rebels in} Afghanistan. He was a burr under the saddle," Humphrey concluded.

Another of Pillsbury's senatorial supporters said that as the Pentagon's representative on the interagency "208 Committee" that oversees covert action, Pillsbury clashed with North over the administration's Nicaragua policy and objected that North was violating standard procedures.

According to the senator, it was shortly after a shouting match with North that Poindexter accused Pillsbury of leaking classified information.

Pillsbury does not easily submit to questions about his future, but does admit, if pressed, to a desire to rejoin the administration. "I have a lot to learn about the human dimension of Washington policy struggles," he said. "But the lessons I have already learned could be put to good use in the Reagan administration and its successors."