Gen. Alexander M. Haig Jr., Ronald Reagan's nominee to be the next secretary of state, brings an unusual record to this new assignment. Though Haig has been thoroughly exposed to foreign policy issues under five presidents from Kennedy to Carter, he has never played the part of a traditional diplomat.

On the contrary, much of Haig's experience in foreign policy and national security matters came under circumstances in which he and his superiors were deliberately acting outside normal diplomatic channels. In two cases where Haig played an important personal role -- asecret aspects of the Nixon administration's policies in the Indochina war and in Chile -- part of his responsibility was to exclude State Department officials from any knowledge of what he was doing. The wiretapping program that Haig oversaw for the Nixon White House included taps on the phones of several American diplomats.

Haig's record includes a direct role in the secret bombing of Cambodia, personal urging of the Christmas bombing of 1972 around Hanoi and Haiphong, and active involvement in the Nixon administration's secret attempts to influence Chilean elections and then to prevent elected Marxist President Salvador Allende from coming to power, finally by trying to promote a military coup.

Until the 1974-79 period, when Haig was supreme allied commander in Europe, most of his career was spent as a staff man. One of the first men Haig served as a staff aide was Gen. Alonzo Fox, his father-in-law. In the Kennedy administration he worked in the Pentagon for Cyrus R. Vance (then general counsel of the Department of Defense) and Joseph A. Califano Jr. (general counsel of the Army.)

In 1969, at Califano's urging, Henery A. Kissinger made Haig his military aide on the National Security Council staff, and in 1970 Haig became deputy national security adviser. In 1973 Haig took over the quintessential staff job -- chief of staff to President Nixon.

In his years of public service, Haig rarely has had to take explicit public positions for giving loyal support to the policies of his superiors. His respect for the "commander-in-chief" is legendary.

Several Democratic senators have said they plan to question Haig about his attitudes as a military man toward traditional diplomcay and about his role in controversial foreign policy actions in the Nixon years at his confirmation hearing next month.

Another issue likely to come up in the confirmation hearings is Haig's attitude toward the role of Congress in foreign affairs. As NATO commander, Haig more than once lectured visiting senators and representatives on the failures of Congress, particularly the arms embargo against Turkey, which he decried as contrary to the interests of the alliance. According to witnesses, Haig was once briefing a Senate delegation when then-Sen. William Scott (R-Va.) suddenly slammed his hand down on the table and said, "Gen. Haig, I hear arrogance coming out of your mouth!"

Haig's many admirers, on the other hand, say he can provide strong, decisive leadership, and that his experience would help him succeed as secretary of state. Haig and Chile

Haig's involvement in covert operations against Chile is partially recorded in the published record of the Senate Intelligence Committee's report on Alleged Assassination Plots Involving Foreign Leaders.

On March 25, 1970, the Cabinet-level 40 Committee (the Nixon administration group that reviewed and passed judgement on top secret covert action projects) approved a joint embassy/CIA proposal recommending that "spoiling" operations -- propaganda and other activities -- be undertaken by the CIA in an effort to prevent an election victory by Marxist candidate Allende, according to a Senate Intelligence Committee report.

In addition to a total of $800,000 to $1 million in covert action funds, International Telephone & Telegraph, fearing the nationalization of its highly lucrative Chilean Facilities, contributed $350,000 and coordinated efforts that proceeded parallel to the CIA scheme.

Outside the 40 Committee's members (the national security adviser, the secretaries of defense, state and treasury and the CIA director), only the U.S. ambassador to Chile, Edward Korry, and a small cadre of CIA operatives were aware of the activities. But, according to sources familiar with the Intelligence Committee's investigations, another person at the White House was aware of the project -- Haig, who was the regular liaison between the NSC staff and the CIA on this and most other sensitive projects.

The covert campaign to influence the Chilean election was unsuccessful, and Allende won a plurality of the popular vote. After the election the 40 Committee met again to discuss "what action should be taken prior to the October 24 congressional vote" that would confirm Allende's election and install him in power. The committee authorized another series of covert moves, including political, economic and propaganda activities designed "to induce Allende's opponents in Chile to prevent his assumption of power, either through political or military means."

Against, knowledge of these activities was restricted to a tiny group, and Haig was the regular contact point at the NSC staff for the secret operations.

On Sept. 15, President Nixon told "CIA director Richard Helms that an Allende regime in Chile would not be acceptable to the United States and instructed the CIA to play a direct role in organizing a military coup d'etat in Chile to prevent Allende's accession to the presidency." Helms testified to the Senate Intelligence Committee, "If I ever carried a marshal's baton in my knapsack out of the Oval Office, it was that day."

Thus began a second chain of covert actions parallel to those authorized by the 40 Committee, the so-called "Track II" as it was known by Nixon, Kissinger and Haig. Track II was to be so secret that Nixon told Helms to tell no one in the State Department about it, not even the secretary of state or the U.S. ambassador to Chile. Nixon also told Helms to hide Track II from members of the 40 Committee, who were formally charged with approving such secret actions.

Instead, Helms, had the CIA's deputy director for plans (covert action), Thomas Karamessines, provide Kissinger and Haig with regular briefings on developments in Track II. According to informed sources, the Intelligence Committee investigation concluded that Haig was the facto "executive officer" of Track II, keeping tabs on it for the president.

What Karamessines reported to Haig (and to Kissinger on the few occasions he was in town during that period) was this:

The CIA had 21 contacts with key military and police officials inclined to stage a coup attempt and gave them assurances of "strong support at the highest levels of the U.S. government." The "major obstacle" facing the military conspirators was "the strong opposition to a coup by the commander in chief of the army, Gen. Rene Scheinder, who insisted the constitutional process be followed."

The CIA's agents suggested that Schneider could be removed. Their Chilean contacts then devised a coup plan, beginning with the abduction of Schneider, that the CIA endorsed.

On Oct. 15, Karamessines met with Kissinger and Haig at the White House and reported in detail, according to the CIA record of the meeting, on "the general situation in Chile from the coup-possibility viewpoint." One particular plot by a group of conspirators led by a Chilean general named Roberto Viaux was discussed. All present at the meeting agreed that the Viaux plot should be turned off for the time being.

But it was too late to turn off the Viaux plot and his group made two unsuccessful attempts to kidnap Scheider. Another group of military plotters affiliated with the Viaux group and encouraged by the CIA then tried its own plan to kidnap Schneider and in the accompanying skirmish, Scheider was killed.

Kissinger and Haig have denied any responsibility or foreknowledge of the second coup group which assassinated Scheider.

The Senate select committee's investigative files on these events reveal fundamental contradictions between the testimony of Haig and Kissinger on one hand and CIA officials on the other. The most significant conflict is about the Oct. 15 meeting.

Haig and Kissinger, according to the Intelligence Committee, "testified that on Oct. 15, 1970, the White House stood down CIA efforts to promote a military coup d'etat in Chile. Both testified that after that date they were neither informed of, nor authorized, CIA Track II activities, including the kidnap plans for General Schneider. . . ."

"By contrast, CIA officials testified that they operated before and after Oct. 15 with the knowledge and approval of the White House."

Kissinger testified not only that he turned off the coup plan but also that "he was informed of no coup plan which began with the abduction of General Schneider." He was aware of Viaux's plan -- which he and Karamessines decided on Oct. 15 to try to forestall -- but did not know that it was to begin with Schneider's abduction.

According to the report, "General Haig's testimony generally coincided with Kissinger's recollection." Haig's full testimony has never been made public.

But CIA officials insisted to the Intelligence Committee that "close consultation" with Kissinger and Haig continued throughout.

The Intelligence Committee's report raises another question on the matter of White House authorization of the Vaiux group's kidnap attempt. This was the plot that the United States tried to call off after the Oct. 15 Kissinger-Haig-Karamessines meeting. The question is who, if anyone, in the White House originally cleared the CIA to give Viaux the go-ahead?

The most recent previous contact between Karamessines and the White House that the committee's investigators could learn of was with Haig Oct. 10. But Haig testified that he had given no authorization for the Viaux plot Oct. 10.

Apparently, the Senate Intelligence Committee was unaware that President Nixon's secret White House logs -- logs that The Washington Post has seen -- show that Karamessines met privately with Nixon himself at 11:05 a.m. on Oct. 13. Although the logs do not list. Haig as a participant in that meeting, given his intimate involvement in Track II at the time, he would be an excellent witness on the subject of the meeting. Apparently, Haig has never been asked to explain this sequence.

Karamessines has testified that "Track II was never really ended," a statement that has never been fully clarified. Karamessines also testified that he met with Haig on Oct. 19, 1970, when he "would have" told Haig about the second coup group's plan that resulted in Schneider's assassination three days later. Haig denies ever learning of any plan to kidnap Schneider.

Another unresolved Chilean matter is the never-publicized accusation by former ambassador Korry that nine assassination attempts grew out of Track II, including one against Allende. Haig and Indochina

From the beginning of his service on Kissinger's National Security Council staff, Haig was intimately involved in the conduct of the Indochina war. After the American invasion of Cambodia in 1970, Haig became a principal link between the Nixon administration and President Lon Nol of Cambodia, urging the Cambodian in a series of personal meetings to build up his army and continue fighting the North Vietnamese. In the last stages of the American involvement, when Kissinger was trying to tie up a peace agreement with North Vietnam, Haig differed with his mentor, recommending tougher negotiating positions and harsher military actions than Kissinger favored.

Haig was present at the initial breakfast meeting in the Pentagon in early 1969 where a secret bombing campaign against Vietnamese sanctuaries in Cambodia was discussed. This led to Operation Breakfast, then to Operation Menu, both clandestine bombing operations that continued for many months. Defense Department records were altered to hide these operations, and Congress was not told of their existence. Haig was in on them from the beginning.

In early 1970, when the White House was considering possible moves against the sanctuaries in Cambodia, Haig gave orders to the Pentagon officials involved that they tell the State Department nothing about these deliberations, according to the military aide to Melvin Laird, then defense secretary.

According to White House officials who worked with Kissinger and Haig, Cambodia was Haig's special responsibility, particularly when it became an active battleground after the Lon Nol coup that overthrew Prince Norodom Sihanouk in early 1970. Lon Nol never had an easy time mobilizing or leading his country, and it fell to Haig to personally reassure and encourage him, and also to oversee for the White House efforts to bolster the Cambodians.

Haig's first personal mission abroad for the White House was a trip to Cambodia in May 1970, just after the beginning of the U.S. offensive into Cambodian territory. Haig set the pattern for his role on that first trip by declining to invite the American charge d'affaires in Phnom Penh, Mike Rives, to accompany him when he met with Lon Nol, and declining to tell him after the meeting what had transpired.

Later a Korean war acquaintance of Haig's Jonathan (Fred) Ladd, was invited by Kissinger to become the civilian chief of the American military aid program in Cambodia. Ladd took the job. Later in Phnom Penh he dealt directly with Haig in Washington, sometimes without the knowledge of his diplomatic superiors.

According to White House officials who worked with Haig at the time, the general privately accused both of his bosses -- Kissinger and Nixon -- of being too "weak" on Vietnam. Haig repeatedly encouraged Nixon to be tough with the North Vietnamese, offering harder-line advice than any of Nixon's other intimate advisers. For example, Haig was an ardent proponent of the 1972 Christmas bombing around Hanoi and Haiphong.

Colleagues from Haig's White House days say that Haig often urged military action in policy deliberations involving other parts of the world, too. Military solutions have appealed to Haig more recently; in January 1979, when he was the NATO commander in Europe, Haig recommended that the United States encourage the Iranian military to take control of the country.

On the other hand, Haig has often said privately that it fell to him to restrain both Kissinger and Nixon during his White House service. If the Senate Foreign Relations Committee tries to determine precisely what policy advice Haig himself gave in those years, Haig could face a delicate choice between revealing the advice he gave President Nixon or asserting executive privilege.