North Atlantic Treaty Organization defense ministers today for the first time formally and unanimously linked Soviet international behavior to the start of arms control negotiations.

In a precedent-breaking oral statement that not only went outside their fixed agenda but also was unusual for its addressing a current crisis, the 15 ministers meeting as the Nuclear Planning Group said that Soviet intervention in Poland "would gravely undermine the basis for effective arms control negotiation."

The statement, which came a day after Warsaw Pact maneuvers in and around Poland reportedly ended, was hammered out only after much controversy. It served explicit notice that the alliance by no means feels the Polish crisis is at end.

At the same time, it gives the Reagan administration another excuse for putting off U.S.-Soviet talks on reducing the nuclear weapons in Europe, a subject of considerable sensitivity for the United States' European allies.

U.S. officials here hailed the statement as a victory for President Reagan's policy on arms-control negotiations with the Soviets.

NATO Secretary General Joseph Luns, who read the statement, told a press conference here that the ministers were serving notice on the Soviets that they, as well as Americans, were being held accountable for the future of arms control talks.

"I feel very pleased that the ministers have authorized the secretary general to issue a statement of the kind he just read," Defense Secretary Caspar W. Weinberger said at the brief press conference following this 29th planning group meeting.

"We have no hesitancy about starting the talks," on reducing so-called theater nuclear forces, Weinberger added. "It is a matter of having an atmosphere that indicates the talks would be effective."

West German Chancellor Helmut Schmidt has been at the forefront of NATO leaders urging the United States to start such talks with the Soviets, but his defense minister, Hans Apel, said, "I am satisfied" with the way the planning group dealt with the question.

Apel noted that the two-track approach of negotiating to reduce theater nuclear weapons and at the same time planning to deploy new ones was reaffirmed in the formal, written communique issue after the two-day meeting.

This is how the oral communique linked Soviet behavior in Poland to arms control negotiations:

The defense ministers "noted with great concern that the Soviet Union for the past weeks has been engaged in increasingly menacing troop movements and other threatening activites around Poland.

"The ministers stated that actual intervention, including the use or the threat of use of military force, are incompatible with the professed Soviet desire for peace and disarmament and are inconsistent with the Helsinki Final Act and the United Nations Charter."

Recalling the statements of the defense and foreign ministers in December 1980, they reaffirmed that any Soviet military intervention would pose a serious threat to security and stability and would have profound implications for all aspects of East-West relations.

"In particular, we agree that the Soviets would gravely undermine the basis for effective arms control negotiations if they were to intervene in the internal affairs of Poland. Poland should be free to decide her own future."

The back-room debates in drafting the statement were fierce at times, according to NATO officials who declined to be identified. However, one U.S. official said that the United States came in with several formulations but ended up with one that achieved the two primary American objectives.

The first, he said, was to link Soviet behavior in Poland to the future of arms control talks. The second, he continued, was to keep the planned modernization of the theater nuclear arsenal in Europe on schedule. The United States intends to add Tomahawk land-based cruise missiles and Pershing II battlefield rockets to its theater forces in Europe.

Weinberger noted at another point in the press conference that the formal, written communique recommitted the NATO alliance to deploying the new theater nuclear weapons on schedule.

British Defense Minister John Nott told The Washington Post in an interview that "while this tenseness of the situation exists in Poland, it's impossible to talk about dates" for opening arms talks on theater nuclear forces. "But the position may be clearer in two or three weeks' time if we can see a genuine relaxation in the tension in Poland and a clear indication that the Soviets are no longer building up their state of readiness around Poland."

The formal communique said the "ministers emphasized that NATO will move ahead with its planned schedule of long-range theater nuclear-force modernization while at the same time making efforts to reach balanced, equitable and verifiable arms control agreements limiting such forces as was decided on Dec. 12, 1979.

"They expressed the hope that the balance could be achieved at lower levels of armaments," the communique added.

The defense ministers in the formal communique also:

Expressed regret that the Soviets have stepped up their deployment of the SS20 intermediate-range missile. The ministers said 220 of them have been deployed, 20 more than previous estimates of the three-warhead missile. Previously, NATO officials have said two-thirds of the SS20s have been aimed at NATO countries in Europe.

Supported "all steps necessary to ensure an adequate balance" of U.S. and Soviet strategic forces. No mention was made in the communique or in the press conference of continuing the commitment of NATO nations to increase their defense budgets by at least 3 percent a year after allowing for inflation. The Carter administration considered this commitment its major achievement in NATO, while several countries felt such a figure was misleading if not an insult, to their military efforts.

Rejected the Soviet proposal to declare a moratorium on theater nuclear weapons, declaring this did not address "the fundamental problems caused by the buildup of Soviet arms."

The two-day Nuclear Planning Group meeting that ended today was Weinberger's first. Several European defense ministers gave him high marks for his sensitivity to European concern, although one German official said that "we deserve special consideration because we are on the firing line." Many German officials are anxious to obtain a fixed date for opening U.S.-Soviet talks on reducing theater nuclear weapons.