President Bush and Soviet President Mikhail Gorbachev declared yesterday that they have launched superpower relations into a new phase of cooperation and stability marked by a deepened personal rapport, but acknowledged that their differences over Germany and Lithuania were not surmounted at the summit.

Seated before an audience of senior advisers and journalists in the White House East Room for a news conference televised live in both nations, the two leaders sprinkled their remarks with expressions of respect for each other. "We have established a rapport," Gorbachev said, recalling that at the last Washington summit he had concluded that Bush "is the kind of person to do business with." Bush said, "We've moved a long, long way from the depths of the Cold War."

For all the personal chemistry on display, both leaders also conceded that underlying frictions remain as the relationship changes and the Cold War map of Europe is redrawn. "I'm not sure we narrowed them," Bush said of disagreements over the future alignment of a unified Germany, which he has insisted be part of the North Atlantic Treaty Organization. "We could not resolve this issue in Washington," the Soviet president agreed.

Gorbachev delivered an emotional appeal that the Soviet Union not be isolated by the West as the new European order is shaped. He warned "in no uncertain terms" that any plan for Europe "would be doomed" without both superpowers' "active participation."

Gorbachev also insisted that the death in World War II of 27 million Soviet citizens gives Moscow "a moral right" to insist on security guarantees once Germany is reunited so that "everything that was obtained at such tremendous cost, that so many sacrifices would not spell new perils."

Asked about the emotional issue of emigration by Soviet Jews to Israel, Gorbachev raised the possibility of slowing the flow of exit visas unless Israel heeded Arab complaints about resettlement of the emigres in territories occupied by Israel. He said Moscow is being "bombarded by a lot of criticism" in "acute terms" from Arab leaders about this. Israel denies making any deliberate effort to steer the Soviet Jews to the occupied territories.

Gorbachev's comments brought quick protests from Israel and from American Jewish groups. Bush reiterated that the United States opposes settlement in the occupied territories, a long-standing matter of dispute with Israel.

Bush was on the defensive about his surprise decision at the summit to sign a trade pact with Moscow even though the Soviet Union has not relaxed its economic embargo against Lithuania. He acknowledged that he will not make Lithuania an issue in deciding whether to grant most favored nation trade status to the Soviet Union. He described Lithuania as one of "the political problems we face" from Congress. "We've got a Congress that has its rights," he said.

Bush said his only condition for approving most favored nation status is Soviet passage of a long-delayed law codifying Soviet emigration policy.

Bush said he had protested the Soviet economic blockade of Lithuania but received no assurances from Gorbachev that it would be lifted.

Gorbachev had lobbied Bush hard for approval of the trade pact from their first meeting on Thursday, even though the accord itself will have little practical affect until the trade status is approved.

Bush described the disagreement over Lithuania's efforts to gain independence as "one of the thorns" in the U.S.-Soviet relationship. He noted that the United States has never recognized the incorporation of the Baltic states into the Soviet Union, but he did not press Gorbachev in the news conference to begin a dialogue with the Lithuanian leaders, which Bush has sought previously.

Gorbachev vowed not to give in to the demands for immediate secession. Although he had recently suggested to a group of Lithuanian legislators in Moscow that independence might be achieved in two or three years, yesterday he took a hard line, saying "no fewer than five or seven years would be required for us to sort things out" after "divorce proceedings."

Gorbachev cast the Lithuanian bid for independence as a fundamental challenge to his responsibilities under the Soviet constitution. "I keep saying that President Bush would have resolved an issue like this within 24 hours, and he would have restored the validity of his constitution within 24 hours on any state," he said.

In forceful and animated answers, Gorbachev also confronted much of the Western skepticism about his program of restructuring, or perestroika, and the doubts about his own position in the face of public discontent and the rise of populist Boris Yeltsin to an important political post. This remarkable airing of his problems was punctuated by a question to Gorbachev about Yeltsin from a Soviet correspondent for Izvestia, the government newspaper. Seeming startled that it even came up, Gorbachev said, "I don't think you have choosen the best place for clarifying our internal problems." He then shrugged it off with, "C'est la vie," and questioned whether Yeltsin's latest statements were sincere.

Appealing for understanding from his American audience, Gorbachev said of his reforms, "I don't think we have ever tackled a task like this in the history of our country."

"At this point in time, the Soviet Union is deep into profound change. . . . We are walking away from one particular way of life, toward different forms of life. We are changing our political system. We are introducing a new model in economy," he said, describing his goal as making the Soviet Union "more open to the outside world."

The accompanying tumult "confirms not only the fact that we're cleaning up our courtyard, we're really revamping our entire society," he said. "How long will Gorbachev stay in his office?" the Soviet president asked in a rhetorical reference to the doubts about his political survivability. "Even this, I think, fits into this process of profound change." With a twinge of irritation, he added, "And perhaps this is something we cannot do without."

From the opening ceremony of the summit last Thursday, Bush praised Gorbachev as an agent of change not only in the Soviet Union but around the globe. Gorbachev echoed this view yesterday. "Today the pivotal point of world politics is perestroika in the Soviet Union," he said.

The leaders promised to hold regular summits. Gorbachev invited Bush to visit the Soviet Union but Baker said a date for the next meeting had not yet been set. The two presidents also hailed the agreements they reached on reducing chemical weapons and strategic nuclear arms.

On the issue of Germany, Secretary of State James A. Baker III later disclosed that in the summit talks Gorbachev floated a "very vague" suggestion that NATO and the Warsaw Pact reach a new "political agreement" to assuage Soviet concerns about future European security arrangements. He said the Soviets offered no details and while the United States is willing to explore it, such an agreement could not supplant the security role of the Western alliance. A senior U.S. official said later that the idea was viewed as one of many, including nine points presented to Gorbachev at the summit by Bush, that would defuse Soviet fear of a resurgent Germany.

Although they did not bridge their disagreement over Germany, both leaders said they found it worthwhile to air views face-to-face. When they last met at Malta, the hard-line communist regimes of Eastern Europe were just beginning to collapse. This was the first U.S.-Soviet summit devoted to discussion of a new European security order as Moscow's old allies, Poland, Hungary, East Germany and Czechoslovakia, move toward democracy.

Bush said in his opening statement that he and Gorbachev are in "full agreement" that a united Germany's alliance membership is "a matter for the Germans to decide," as provided in the 1975 Helsinki Final Act. A senior administration official said that when Bush made such a statement during the summit discussion of Germany on Thursday, Gorbachev agreed with him that it should be left to the Germans.

But as Gorbachev talked about Germany in the news conference yesterday, he also insisted that the West could not simply impose its alliance on the new German state. If Western-alliance membership for Germany is "the only option," he said, "and some would like to impose it on us," then the Soviet Union would reevaluate its willingness to reduce conventional weapons in Europe at the negotiations in Vienna.

Gorbachev again asserted that Germany's future alignment could be decided in the continuing talks by the two German states and the four victorious World War II allies. The United States has resisted this.

U.S. officials said the two leaders talked extensively about Germany on the first day of the summit and never returned to it at any length. They said the administration now assumes that months of negotiations will be required to settle Germany's status.

Marshal Sergei Akhromeyev, a top military adviser to Gorbachev who participated in many of the summit meetings, said yesterday that one option offered by the Soviets was to strip NATO and the Warsaw Pact, of their military functions and make them purely political organizations. He said the military command of each alliance would be disbanded. U.S. officials said the Soviets also suggested that Germany be made a member of both alliances.

Baker, appearing on NBC News's "Meet the Press," was asked about a recent Soviet suggestion that Moscow apply for NATO membership. He recalled that the Atlantic Charter, NATO's founding document, calls for membership by full democracies, and the Soviet Union, "while they're moving toward democracy and openness, might have some distance yet to go to meet that qualification." Baker said he had to "wonder out loud" whether Moscow would be willing to put Soviet forces under NATO control since an American traditionally serves as supreme allied commander.

Staff writers R. Jeffrey Smith and Don Oberdorfer contributed to this report.