WASHINGTON — President Bush has announced he will make the first visit to Israel of his presidency at a time when America’s close ally is re-entering negotiations to relinquish the land it won in the Six-Day War, and amid worries international diplomatic efforts against Iran’s nuclear program are on the verge of collapse.

First reported in the Israeli press yesterday, The New York Sun confirmed from American officials that the visit is in the offing. It is scheduled for January. On the heels of a new American intelligence estimate on Iran’s nuclear weapons program that could scuttle a third U.N. Security Council resolution against the Islamic Republic, the visit will be a powerful symbol to Tehran, whose leadership has pledged to destroy Israel.

Mr. Bush yesterday signaled that his press to end Iran’s enrichment of uranium would continue despite the new National Intelligence Estimate that considers the Iranian uranium enrichment at Natanz to be separate from its nuclear energy program.

“I still feel strongly that Iran is a danger,” Mr. Bush said. “Nothing has changed in this NIE that says, ‘Okay, why don’t we just stop worrying about it.’ Quite the contrary. I think the NIE makes it clear that Iran needs to be taken seriously as a threat to peace. My opinion hasn’t changed.”

The opinions of the Chinese and the Russians — two permanent, veto-wielding members of the Security Council — may have changed, however. China’s ambassador to the United Nations, Wang Guangya, said yesterday: “We want to learn more from our U.S. colleagues. … Certainly I think we’ll study the content and also think about the implications for the council action.”

President Putin yesterday met with Iran’s chief nuclear negotiator, Saeed Jalili, and said he was pleased with Iranian cooperation with the International Atomic Energy Agency, a statement that hints Russia would be unwilling to support sanctions against Iran’s enrichment at Natanz.

For Israel, the new doubts on whether Iran is now building a nuclear weapon could scuttle the Jewish state’s strategy of supporting international pressure on Iran, counting on a combination of sanctions, threats, and censure to prompt Tehran to end its pursuit of a nuclear weapon.

In an interview yesterday, a former defense minister, Ephraim Sneh, said the new NIE would hurt the diplomatic efforts against Iran. “I am afraid that those countries that want to evade cooperation with the United States may use this as a pretext not to support a third resolution,” he said.

Mr. Sneh said he still advocates a policy whereby Israel will “rely on itself to develop indigenous capacities to defend itself and deal with the problem.” Israel has procured advanced fighter planes and submarines capable of launching missiles from America since at least the 1980s largely as a military response to the threat of an Iranian atomic bomb.

On Tuesday, Israel’s current defense minister, Ehud Barak, told reporters he believed Iran did have an active weapons program, conceding that a distinct weaponization program may have been suspended in 2003, as the new American estimate says, but adding that Israeli intelligence believed the weapons program has restarted since then. The new NIE expresses only “moderate confidence” that the weapons program has not restarted.

“The bottom line is that words don’t stop missiles, actions do,” Mr. Barak said. “And there is much that needs to be done regarding the Iranian nuclear program. We need to take action in applying sanctions, in exercising diplomacy, and in other venues as well.”

He added, “We cannot allow ourselves to rest just because of an intelligence report from the other side of the earth, even if it is from our greatest friend.”

A State Department official yesterday who requested anonymity said the new estimate presented “a bump in the road” for efforts to pass a third U.N. resolution against Iran. Secretary of State Rice in September said the five permanent members of the U.N. Security Council would wait until reports from the International Atomic Energy Agency and the European Union and then begin work on a draft resolution.

“This is more a bump in the road than a brick wall,” the State Department official said yesterday. “This is not a dramatic change in direction. We will continue to seek to increase the pressure on the Iranian regime to suspend verifiably its enrichment program and accept the generous offer that has been on the table since June 2006.”

That offer promises America will participate in negotiations with Iran in exchange for Iran’s promise to end enrichment. The Russians have offered to enrich Iran’s uranium for a nuclear reactor under the condition that the Russians control the production of highly enriched uranium, a fuel that can be used for peaceful energy and nuclear weapons.