LONDON, JULY 6 -- Leaders of NATO's 16 nations today pledged broad changes in their military and political strategy in a landmark declaration designed to respond to the dramatic transformation sweeping Europe.

President Bush, who proposed the original draft of today's statement and pressed for its approval in close cooperation with West Germany's leaders, called it a "historic turning point" that charted "a new path for peace."

While insisting on retaining enough arms to defend themselves in case of attack, NATO's leaders promised to "profoundly alter the way we think about defense."

In a communique summing up agreements at the two-day summit that were even more sweeping than some earlier forecasts, they committed themselves to sign a nonaggression declaration with individual Warsaw Pact nations, invited Soviet President Mikhail Gorbachev and Eastern European leaders to visit NATO headquarters in Brussels and to assign regular envoys there, and promised to expand the role of the Conference on Security and Cooperation in Europe, the forum used for negotiations by 35 nations on both sides of what was the Iron Curtain.

Using language proposed at the last minute by West German Chancellor Helmut Kohl, they further promised to add a firm limit on the size of a united Germany's armed forces to an agreement under negotiation to cut American and Soviet conventional forces in Europe. The West Germans believe the troop limitation plan could provide the last piece in the package of measures to sway Gorbachev into accepting German unification, a U.S. official said.

The leaders also pledged to reduce their reliance on nuclear weapons, including eventual removal of nuclear-tipped artillery shells from Europe, and to cut back and withdraw conventional forces in tandem with the Soviets by the end of this year if possible. They agreed to modify the defense doctrine that for more than two decades has guided the alliance's strategy by pledging that nuclear weapons would only be used as a "last resort" in the event of war.

The declaration's main aim was to cement the startling changes in the communist world by extending "the hand of friendship" to Gorbachev and the nations of the former East Bloc, NATO's erstwhile adversaries. It also sought to smooth the way toward German unification within NATO by assuaging Soviet fears about both the alliance and the new Germany's military potential.

At the same time, Bush and his fellow leaders sought to reassert the influence in the new Europe of NATO and the United States against those who contend the alliance has no further purpose and should be disbanded now that the Cold War is ending.

"For more than 40 years we've looked for this day," said Bush at the close of the conference. ". . . And now that day is here, and all peoples from the Atlantic to the Urals, from the Baltic to the Adriatic, can share in its promise."

In a press conference at the close of the meeting, Bush said he believed the declaration would help Gorbachev overcome those in the Soviet Union who still see NATO as a threat.

"I would think he would view this as a very positive step forward, and one that vindicates some of the moves that he's made over the past year or two," said Bush.

The president also put himself in Gorbachev's shoes for a moment and offered some free advice, one politician to another, on how to sell the new NATO to the Soviet Union's generals and to the Soviet people.

Said Bush: "I would think he could say, 'We've been right to reach out as we have tried to do to the United States . . . {and} countries in Western Europe. They're changing. They have changed their doctrine because of steps that I, Mr. Gorbachev, have taken. And I get on the offense.' Then let the rest of us help him with some of his hard-liners."

But despite kind words for Gorbachev, Bush reiterated his deep doubts about sending American economic aid to Moscow, saying he objected to the vast amounts of money the Soviets spend on defense and to the $5 billion per year they allocate to Cuba.

"I have some big problems on that one," said Bush. "I think the American people do."

Gorbachev sent a letter to British Prime Minister Margaret Thatcher on the eve of the summit making his most direct plea yet for help in bailing out his reform program. White House National Security Adviser Brent Scowcroft expressed some irritation about the letter in an interview with Cable News Network today.

"I think it's partly a ploy," said Scowcroft. "It's a clever thing to do, to try to co-opt the West into helping him with his problem."

The White House stance was at odds with that of West Germany's Kohl, who wants to see a major package of Western aid, perhaps as much as $15 billion, as part of the deal to win Soviet acquiesence to German unity. While rejecting that proposal, Bush told reporters he had no objection to direct German assistance to Moscow.

While the issue did not come up formally during this summit, Kohl and his aides repeatedly stressed Gorbachev's financial needs in informal discussions with other officials and with reporters. While it is certain to be an issue at the economic summit meeting of seven major industrialized nations in Houston next week, Kohl indicated today he recognizes that a final decision on a collective aid package would not be made there.

"We are not under time pressure," he told reporters here. "It is a question that will reach a decisive phase -- when you have to ask each government in concrete terms, 'What are you prepared to do?' -- at the end of the year."

{On a flight from London to Houston tonight, Bush was informed that Soviet Foreign Minister Eduard Shevardnadze said that NATO's "decisions . . . move in the right direction and pave the way to a safe future for the entire European continent," the Associated Press reported. The president said of that reaction: "That's very interesting. And very positive." Bush confided he had received a recent communication from Gorbachev, but merely winked and smiled when asked to describe its contents.}

Aside from that one dispute, however, American and West German leaders worked closely together throughout this summit orchestrating the agreement and overcoming reservations expressed on some key issues by Britain and France.

One important dispute that was smoothed over concerned Bush's proposal to modify NATO's longstanding doctrine of "flexible response" by declaring nuclear arms to be weapons of "last resort." Thatcher and French President Francois Mitterrand vehemently opposed the change, which Thatcher believed would weaken NATO's ability to deter aggression.

Thursday night, however, foreign ministers agreed to language that retained Bush's "last resort" wording while adding at the insistence of the British a sentence reaffirming "there are no circumstances in which nuclear retaliation in response to military action might be discounted."

The resulting paragraph seemed contradictory and ambiguous -- which was exactly what British officials said was needed in order to maintain the deterrent effect of the alliance's nuclear doctrine. It was thus portrayed as a minor triumph for the British, who otherwise conceded privately that West Germany, aided and abetted by the United States, had won virtually everything it had sought here.

"The thrust of the declaration is exactly what they wanted, while we got some of the fine print," said a British official.

Thatcher said she was satisfied. Mitterrand, who said France would keep its own independent strategy for when and where to use nuclear weapons, was not. "France doesn't accept this -- or yesterday's nuclear doctrine," he said. France withdrew from NATO's military structure in 1966 but remains under the alliance's political umbrella.

At his own press conference today, a satisfied Chancellor Kohl said the summit would help bring about speedy German unification. "Everything which improves the atmosphere between East and West will smooth our path towards unity. We will be in a much better position to talk to the Soviet leadership," said Kohl, who will travel to Moscow in a week to try to nail down a unity deal.

Kohl was effusive in his praise of the Bush administration. "The present administration has a very clear vision of things," said Kohl. "They are not just talking self-determination, they mean self-determination." The United States, he added, has a government "that knows what history demands," and he pledged that American influence in Europe would endure. "In a continent of Europeans," Kohl said, "Americans will have a permanent residence or an apartment."

One of the cornerstones of American influence in Europe has been its commitment of U.S. troops and nuclear weapons. Bush said today that despite some calls to save money by bringing U.S. soldiers home, it was important that they remain as long as the Europeans want them to.

"I view it as my responsibility to make clear to the American taxpayer why it is in our interest to help keep the peace," he said.

NATO is dispatching its secretary general, Manfred Woerner, to Moscow on July 14 to symbolically deliver the new declaration and convey the alliance's invitation to Gorbachev to come to its Brussels headquarters. It will be the first visit by a NATO chief to the capital of the organization's onetime principal foe.

The declaration's provisions include a commitment to move away from NATO's strategy of "forward defense" to smaller, more mobile units of multinational forces. A senior U.S. official said the language fit a Pentagon plan, still under review, to eventually reduce American ground forces in Europe to two divisions of highly mobile, "quick response" units.

It also includes a U.S. proposal to eliminate all of its short-range nuclear artillery shells from Europe, provided the Soviet Union does the same.

NATO IN BRIEF

NATO leaders proposed to the Soviet-led Warsaw Pact a joint declaration saying they are no longer adversaries and reaffirming the intention to refrain from threat or use of force.

The leaders pledged to use nuclear weapons only as a "last resort." This major policy change is designed to reassure the Soviet Union.

Western leaders invited Soviet President Mikhail Gorbachev to address a meeting of the alliance, probably in December. In Moscow, Gorbachev said he was always ready to go.

NATO said it would get rid of nuclear-tipped artillery shells in Europe in return for a reciprocal arrangement by the Soviet Union.

Once the United States and the Soviet Union sign a treaty to limit the number of troops in Europe, talks will begin on reduction of a unified Germany's army.

The Western countries invited the Soviet Union, Czechoslovakia, Hungary, Poland, Bulgaria and Romania to establish regular diplomatic liaison offices with NATO.

Despite reported requests from Gorbachev for financial assistance, summit participants offered no direct aid to the Soviet Union.