WASHINGON (AP) President Bush pledged yesterday to slash the United States" nuclear arsenal by two-thirds, to as few as 1,700 warheads, and Russian President Vladimir Putin said he might "respond in kind." Despite the American gesture, Putin renewed his opposition to U.S. missile shield plans.

In private talks, a special White House tour and an East Room news conference, the leaders opened a three-day visit that will focus on the budding U.S.-Russian alliance against terrorism and nagging differences over the 1972 Anti-Ballistic Missile Treaty.

"Together, we"re making history as we make progress," Bush said. "We"re transforming our relationship from one of hostility and suspicion to one based on cooperation and trust."

The talks move today to Bush"s ranch in Crawford, Texas, where U.S. officials held out some hope for accord on the missile shield issue. Both leaders indicated their relationship had buried vestiges of the Cold War.

In his fourth meeting with the U.S. president, Putin urged his own citizens to stop looking at American relations "from the old standpoint, distrust and the enmity." On the question of allowing U.S. forces to use Central Asia as a base into Afghanistan, the Russian president said: "We have nothing to be afraid of."

Earlier, Bush took Putin on an unscheduled tour of the White House, including its swimming pool and the South Lawn tree swing where Amy Carter and the Kennedy children once played. They ducked into a Cabinet Room meeting with their respective delegations, where Bush heaped Putin with praise.

"You"re the kind of guy I like to have in a foxhole with me," Bush said, according to a participant.

Finding plenty of common ground, the leaders urged Afghanistan"s U.S.-backed opposition fighters to use restraint while liberating the nation"s capital of Kabul, and called for a multiethnic post-Taliban government. They brushed aside reports northern alliance forces were executing prisoners of war.

In a blizzard of paper, the pair formalized a series of agreements to combat bioterrorism, bolster the Russian economy, battle money laundering that finances terrorism and strengthen Russia"s ties to NATO the 19-member military alliance formed to counter Moscow in the Cold War.

It was the issue of weapons that underscored their greatest agreement and disagreement.

Bush, who promised in the presidential campaign to significantly reduce U.S. nuclear stockpiles regardless of whether Russia reciprocated, announced his intention to slash the nation"s long-range nuclear arsenal to between 1,700 and 2,200 weapons over the next decade.