The Reagan administration is redirecting its military efforts in the Middle East in the belief that internal subversion is more of a threat to friendly countries, and their oil, than Soviet attack.

The policy shift underpinned the 10-day swing Defense Secretary Caspar W. Weinberger completed Saturday night through Saudi Arabia, Oman and Jordan and has also broadened the charter of the Rapid Deployment Force.

The idea is not to turn to Arab nations at the expense of Israel, as Israeli leaders fear, but to go beyond that relationship in a number of ways to strengthen U.S. relations with Arab countries.

It was in this context that a Pentagon official traveling with Weinberger on his just-completed swing said that the United States could not afford to be held "hostage" to Israel and postpone tightening ties to the Arab world.

"There is no perfect time," said the official in declaring that Weinberger's trip to three Arab capitals had been postponed twice despite the sense of urgency the administration feels about helping already friendly governments in the Arab world and perhaps winning over some others.

The assassination of Egyptian President Anwar Sadat and the near toppling of the pro-western government in Bahrain in December by Iranian-trained Moslem extremists were the latest in a series of events that convinced the Pentagon that the biggest threats to western oil supplies in the Persian Gulf were internal--not external ones that could be combated by sending in the Marines.

"Bahrain was a much closer thing than most people realize," said the U.S. official in declaring that the attempted coup gave impetus to reordering administration priorities for stabilizing the Persian Gulf region. The Bahrain newspaper Akhbar al-Khalij said at the time that the plot was part of a master plan to create disturbances in a number of other Persian Gulf countries, including Saudi Arabia.

Earlier events, the official noted, were Libyan strongman Muammar Qaddafi's advances into Chad; the tripartite pact of Libya, South Yemen and Ethiopia, and threats to Somalia.

All this, the Pentagon official continued, made a direct Soviet attack against pro-western governments in the Indian Ocean theater "look like the least likely threat" to Pentagon analysts.

This represented a change in thinking from 1979, when the seizure of the U.S. Embassy in Tehran made this the big "what if" question: What would happen if Soviet troops, or their surrogates, went on the march to take over oil fields in such countries as Iran and Saudi Arabia.

Rapid Deployment Force planners charged with finding ways to enable American forces to make a stand in the Persian Gulf against the Soviets have recently been given the additional task of assessing ways to combat subversion by lesser powers in the Indian Ocean theater--with Libya's activities among those under study.

The trips of Weinberger and Secretary of State Alexander M. Haig Jr. meshed well in the administration's pursuit of what Haig calls a "strategic consensus" by the United States and pro-western governments in the Middle East, Persian Gulf and parts of Africa on the need to combat both external and internal threats.

Examples:

* Weinberger got Saudi Arabia formally committed to a joint U.S.-Saudi committee to coordinate military efforts. One expected outgrowth is five-year blueprints for structuring Saudi forces; another is assessing together the economic and military needs of other Persian Gulf states.

* Weinberger came close to reaching agreement on a similar joint committee with Oman. His talks with Sultan Qaboos were extremely cordial, according to Weinberger and other involved officials.

* Weinberger seemingly convinced King Hussein of Jordan that the Reagan administration could keep him from becoming dependent on the Soviet Union for arms, holding out Hawk mobile anti-aircraft missiles and General Dynamics F16 fighter planes as possibilities. (When questioned by reporters whether he would ask Congress to go along with selling Hussein mobile Hawks, Weinberger refined his verbal replies and wrote out this response for reporters on his plane: "That is one of the things we will discuss with the king and his commanders. As you know, they have ordered some Soviet equipment because of our ban on selling them mobile Hawks, and it may be that we will want to consider discussing this with the Congress." Reactions from the Israeli government suggest it believed Weinberger had made a firm offer to Hussein.)

* Haig concluded an agreement with Morocco on the same type of joint military committee as was formed in Saudi Arabia and also made progress to gaining access to Moroccan air bases during an emergency in that region.

Washington newspaper columns had suggested that Weinberger and Haig were at odds over the defense secretary's forays into foreign policy on his Middle East trip, but there was no evidence of this in discussions the two had with reporters on their planes. Nor did Weinberger suggest in his conversations with reporters that he was out to punish Israel for such unilateral actions as bombing the nuclear reactor in Baghdad and annexing Syria's Golan Heights.

He was talking to Arab leaders, Weinberger said repeatedly, because the United States needs as many friends as it can get in the vitally important Persian Gulf region.

Despite Tel Aviv's protests about the possibility of U.S. arms going to Jordan, military specialists traveling with Weinberger and Haig stressed that Israel is so far ahead militarily of its neighbors that it has nothing to fear for years from any combination of Arab states. Given that view, and Reagan's conviction that the administration must keep trying to win friends and influence people in the Arab world, the Weinberger trip looks like a success from the president's point of view.