President Carter's commitment of U.S. military power to defend the Persian Gulf "grew out of last-minute pressures for a presidential speech" without detailed study of its consequences and has been "uncritically accepted" by the American public, according to David D. Newsom, who was the State Department's senior career official at the time the policy was announced.

Newsom, who was undersecretary of state for political affairs in 1978-81, said his first knowledge of Carter's bold "Persian Gulf doctrine" came when he saw the State of the Union address in which it was announced on Jan. 23, 1980. He also said the countries in the Persian Gulf were not consulted or even notified in advance.

In an article published today in Foreign Policy magazine, amplified in an interview with The Washington Post, Newsom called the Carter statement "a major new global commitment" for the United States.

Newsom criticized the formulation of the policy and suggested a national debate on its future use, but he stopped short of saying that the Persian Gulf commitment was a mistake. He said in the interview, however, that if he had been asked -- which he was not -- "I would have said this is going further than we were really prepared [to go] under all the circumstances."

He said that his personal unhappiness was well known in government circles, but that while he rasied "some questions" he did not take a position of opposition in intragovernmental meetings because he considered himself a representative of the State Department loyal to a presidential decision.

Newsom, now director of administration and programs at Georgetown University's Institute for the Study of Diplomacy, said it is not unprecedented for a major policy to emerge from the pressure of events and speech deadlines without detailed planning in advance. He cited the Marshall Plan for the reconstruction of Europe in 1947 and President Truman's "Point Four" plan for aid to developing nations in 1949. Neither of these involved a military commitment from the United States, however.

The "Carter Doctrine," as it is sometimes called, followed the fall of the shah of Iran, the seizure of American hostages in Tehran and the Soviet invasion of Afghanistan. As stated in Carter's January 1980 address to a joint session of Congress, "Any attempt by any outside force to gain control of the Persian Gulf region will be regarded as an assault on the vital interests of the United States of America, and such an assault will be repelled by any means necessary, including military force."

In his magazine article, Newsom wrote that "when the Eisenhower Doctrine, which called for the United States to come to the aid of nations requesting assistance when attacked by countries 'controlled by international communism,' was promulgated in 1957, it was extensively debated in Congress and in the media. A joint resolution of Congress ultimately approved the doctrine."

The Carter Doctrine goes further, according to Newsom, because "the United States now decides when to intervene, with or without a request." He said there has been little congressional scrutiny or public debate and "as far as is known, neither the current [Reagan] administration nor the previous one has ever conducted a detailed study of the implications of the policy or its alternatives."

Moreover, Newsom said, at the time of the Carter announcement "the United States had no capacity to back up that commitment with either troops or aircraft based in the region." He called the Carter statement "a formal expression of presidential intent, supporting the creation of a security framework yet to be formed."

That framework is still in the making, with plans for expansion of the Rapid Deployment Force and agreements with several Indian Ocean nations for U.S. military use of their air and sea installations in time of crisis.

The former official raised questions about how extensive the U.S. military backup should be. A thin U.S. presence is a "trip wire" that implies escalation up to the level of a nuclear exchange in case of conflict with the Soviet Union, according to Newsom.

Reviewing the military alternatives available and the policies of European as well as Persian Gulf nations, Newsom said he believes the best U.S. strategy for the time being is to rely on improved U.S. naval forces to back up Carter's commitment.

"A strategy that places U.S. ground forces in the Persian Gulf should not be undertaken without a thorough national and congressional debate," according to Newsom. "That debate has yet to begin."