NATO Secretary-General Manfred Woerner, marking the alliance's 40th anniversary, said Tuesday NATO has ensured peace in Europe for four decades and remains "the backbone and lighthouse of mankind's future in freedom and peace."

Woerner also warned that despite the peaceful intentions of the Soviet leadership under President Mikhail Gorbachev, the East's military potential remains undiminished, and he hoped President Bush would not reduce the U.S. military presence in Europe."It is better to stay here and prevent a war than to leave and come back and perhaps to fight a war," he said. "I think it would be wise to keep the essential American presence in Europe, for political as much as military reasons."

Marking the April 4, 1949, signing of the North Atlantic Treaty, he said in address to a special session of the NATO council, "With our Atlantic alliance being 40 years old today, we celebrate not only an institution but much more a vision - that of peace in freedom.

"This is what NATO has given us. The longest period of general peace that Europe has enjoyed since the days of the Roman Empire.

"Without this alliance, there will be neither stability nor peaceful change," he said. "NATO remains the backbone and lighthouse of mankind's future in freedom and peace."

Woerner said the 16-member Western military alliance had "transformed the ultimate war-fighting weapon into the ultimate instrument of peace-keeping."

"Nuclear deterrence has not merely contained the risk of nuclear war, it has also contained the risk of all war. For this reason it is the bedrock of our security," he said.

At a news conference later Tuesday, Woerner warned of the Soviet military potential even though he praised the intentions of the present Soviet leadership as peaceful.

"There has been a change," Woerner told reporters. "Looking at the current situation, there are the intentions of the current Soviet leadership and these intentions in my eyes are peaceful ones."

"Gorbachev tries to reform his own society and economy. He does not want to wage a war. That's at least what I believe," he said. "Not the least because of NATO, because he and other leaders in the Warsaw Pact know that to wage a war would be too risky for them."

Woerner emphasized the need to maintain a strong Western military alliance.

"There is the risk of an historical process of transition, which you have to calculate," he said. "So we need NATO as a framework of security, as a base of stability in order to make sure that the process of development is peaceful."