The White House for the first time yesterday directly tied the fate of the strategic nuclear arms negotiations with the Soviet Union to the concerted administration concern with Soviet and Cuban military presence in the Horn of Africa.

Presidential national security adviser Zbigniew Brzezinski said that "if tensions were to rise because of the unwarranted intrustion of Soviet power" into the Ethiopian-Somali conflict, "that will inevitably complicate the process" of concluding a new strategic arms limitation talks (SALT) accord.

Brzezinski, the principal administration alarm-sounder on Soviet action in the Horn, said this could affect "not only . . . the negotiating process itself, but . . . any ratification that would follow the successful conclusion of the (SALT) negotiations."

This was the strongest warning ever made by the Carter administration about the international consequences of Soviet military support for Ethiopia.

It was the first time the administration explicitly has pointed to a potential rebound against SALT, the core issue in U.S.-Soviet detente. It was also the first time the Carter administration has so explicitly invoked American political linkage between disperate issues on the U.S.-Soviet scene.

"We are not imposing linkages," Brzezinski said, "but linkages may be imposed by unwarranted exploitation of local conflict for larger international purposes."

White House press secretary Jody Powell said Brzezinski "not only reflects the president's viewpoint, but reiterates simply a statement of the facts of life."

"Inevitably," Powell said, "there is a danger that the behavior of the Soviet Union in the Horn of Africa will affect in a negative way the political atmosphere in this country toward detente and arms limitation. It is a fact of life which I trust the Soviet Union understands. There is a relationship there."

When the Carter administration took office it specifically rejected the geopolitical concept of "linkage" invoked by former president Nixon and secretary of state Henry A. Kissinger. Secretary of State Cyrus R. Vance said the Carter administration no longer would attempt to link negotiations with the Soviet Union to total Soviet actions around the world. Each subject, Vance said, "should be discussed on its own footing."

State Department spokesman Hodding Carter III, maintained yesterday, as Brzezinski and Powell did, that the administration is not reversing course on "linkage."

"As a matter of policy, there is no linkage," Carter said. But "as a matter of a sort of inevitable political effect," he said, Soviet actions in the Horn of Africa are "going to have a spill over effect in Congress and in the nation as a whole."

The Soviet Union insists that it and Cuba are perfectly within their rights in providing military support to Ethiopia at its requests to repel an "invasion" of Ethiopia by Somalia. Somalia says it is responding to appeals for help from Somali ethnic people in the disputed Ogaden region of Ethiopia. American officials concede that Somalia has violated Ethiopia's border, but say what alarms the United States is the presence of Soviet and Cuban military forces in Ethiopia.

Brzezinski said last week that the Cuban military presence in Ethiopia had grown to between 10,000 and 11,000 men, and that a Soviet general was directing some of Ethiopia's military forces. U.S. officials say there are about 1,000 Soviet Military advisers in Ethiopia, with about 400 Soviet tanks and 50 Mig jet fighers sent to Ethiopia.

"This is definitely an external foreign intrusion into a purely regional African conflict," Brzezinski said last Friday.

The significant new development yesterday, however, was the expansion by the Carter administration of the relationships of Soviet actions in Ethiopia to the SALT negotiations.

This came, seemingly by chance, when Brzezinski was called into a breakfast meeting by Vice President Mondale with a group of reporters. Brzezinski was invited to the meeting by Mondale when the reporters asked Mondale about the status of the nuclear arms talks.

It was learned that the Carter administration in fact decided at a meeting of the National Security Council last Thursday to focus greater public attention on Soviet involvement in the Horn of Africa and the danger it raised for increasing world tension.

This coincides with mounting Soviet charges since mid-February that the United States is responsible for the delay in concluding the negotiations on a new nuclear arms control pact to replace the accord that technically expired Oct. 3, but which both sides are respecting.

The Carter administration has rejected the Soviet charges. Brzezinski said yesterday that the United States has made "substantial concessions" in the nuclear talks and has demonstrated its "political will" to make constructive proposals "which will precipitate some debate in the Senate."

"And you know this debate is going to be very intense," he told reporters yesterday.

It is the Soviet turn now, he said, for "an act of political will" to resolve some of the outstanding differences.

"And that, of course," Brzezinski repeated several times, "is bound to be complicated by the overall international context."

What Brzezinski was saying, in effect, was that the administration cannot muster the political support necessary to approve a new SALT accord without new concessions by the Soviet Union, and without an abatement of the pattern of Soviet actions in the Horn of Africa.

This amounts to trying to fulfill two separate objectives. The Carter administration has been unable to devise effective direct measures to head off the expanding Soviet-Cuban involvement in Ethiopia, with an overt American role in the conflict ruled out. At the same time, many congressional experts and administration officials say in private that there cannot be congressional action on a new SALT accord this year in any event, because of the jam-up on the Senate calendar.

The White House congressional liaison team is reported to have advised the administration that the continuing debate on the Panama Canal treaties forecloses any possibility of considering a SALT treaty this year.

Publicly, the administration's position, as repeated by Brzezinski yesterday, is that President Carter continues to hope for a SALT accord before the year is out.

Paul C. Warnke, chief U.S. negotiator on SALT and director of the Arms Control and Disarmament Agency, concurred yesterday with what Brzezinski said, but employed noticeably far milder terminology.

After meeting in closed session with the Senate Foreign Relations Committee, Warnke told reporters, "What Mr. Brzezinski has said is that obviously, if we had a situation such as exists in the Horn of Africa, it makes the negotiating climate far less propitious."

However, Warnke added, "A SALT treaty is not a reward for Soviet good behavior. It's a way in which we advance our own interests." Warnke said the negotiations in Geneva are "making progress. There is no stalemate."

State Department spokesman Carter said there is agreement "at the highest levels" on what Brzezinski said. Vance, he said, has "said essentially the same thing, in different words."