President Bush and Russian President Vladimir Putin rattled around Bush's Texas ranch in a pickup truck and feasted on mesquite-smoked beef Wednesday -- and pressed toward an understanding on U.S. plans to develop a missile defense system.

A day after Bush and Putin agreed to reduce their nuclear stockpiles, White House aides cautioned against expectations of a breakthrough before Putin leaves Thursday. Talks had snagged Tuesday in the summit's opening at the White House, but were still on track, aides said.

In blue jeans and boots, Bush pulled up in a white pickup truck to greet Putin at a helipad on his ranch. "I want to show him some of my favorite spots on the ranch," the president said.

"I still know how to drive," said Bush, who customarily rides in a limousine with a Secret Service agent in the driver's seat. With no horses on his 1,600 acres of land, the president calls himself a "windshield rancher."

On his way to the ranch, Putin stopped at Rice University in Houston to call for closer ties between Russia and NATO. In an address, Putin said the 19-member alliance -- formed to counter the Soviet Union -- could use Russia's help to tackle 21st century threats such as terrorism.

"The leaders of NATO countries now understand that if there is an ally which can bring contribution in confronting those threats, this is Russia," Putin said, suggesting that Moscow could even take part in NATO decision-making.

Bush and Putin are under pressure to reach accord on missile defense. The Pentagon is anxious to conduct tests, even though they would violate the current interpretation of the Anti-Ballistic Missile Treaty, and Bush has told Putin he will seek to scrap the pact early next year if they can't reach agreement.

On the other hand, aides said Bush is considering visiting Russia in the first few months of 2002 -- a sign, perhaps, that the president may be willing to wait that long to strike a deal.

"This is one stop along the road. We'll make other stops after Crawford but each stop is built on the positive results of the earlier meetings," White House spokesman Ari Fleischer said.

One senior administration official said Bush and Putin seemed to reach an understanding -- if not a formal agreement -- that the United States would conduct anti-missile tests under the ABM, perhaps not long after Putin returns to Russia.

Other aides, generally more pessimistic about the talks, said there was no formal accommodation. And yet even these aides said it was more likely than not that Putin and Bush would come to terms -- but not necessarily in Crawford.

The two leaders talked quietly for about an hour Wednesday, almost exclusively about Afghanistan, according to councilor Karen Hughes. The ABM Treaty did not come up, she said.

The White House billed Putin's stay as a friendly visit that would include some informal, private talks between the leaders. The only public event planned was a school visit Thursday at which the leaders were to take questions from students.

Under a gray, rainy sky, the Putins were treated to a Texas dinner of guacamole, mesquite-smoked peppered beef tenderloin, smoked catfish and pecan pie. A country swing band was entertaining a guest list of nearly 30, including Texas politicians, Bush friends, golfer Ben Crenshaw, pianist Van Cliburn and diplomats from both nations.

The Putins were spending the night in the ranch's guest house, built during the presidential campaign alongside the new one-story main house. Bush interrupted the visit to duck into a two-car garage and tell reporters that eight foreign aid workers held by the Taliban, including two from nearby Waco, Texas, had been picked up by U.S. forces and brought out of Afghanistan.

The news of the release, coupled with an announcement that Sunday was National Security Adviser Condoleezza Rice's 47th birthday, added to the evening's festivities.

Bush toasted Putin, saying, "Usually you only invite good friends to your home and that is clearly the case here."

Putin responded in kind: "The U.S. is fortunate at such a critical time in its history to have a man of such great character at its helm."

The visit took place one day after Bush and Putin agreed to shrink their nations' nuclear arsenals by two-thirds.

"If we act together, we will make the world a much safer place than today," Putin said at Rice University.

Bush had hoped that the U.S. cuts, promised during the presidential campaign, would entice Putin to accept his ABM proposal. Under Bush's plan, the United States would remain in the treaty a while longer if Russia agreed to allow the Pentagon to conduct tests and research barred by current readings of the ABM.

The U.S. proposal was a concession of sorts for Bush. He has repeatedly denounced the pact, and his conservative allies want him to scrap it.

Putin's public statements before coming to America suggested an openness to finding flexibility in the ABM.

Bush promised Putin on Tuesday that Russia would be informed of the tests, but Putin asked for more. U.S. officials said he suggested at one time that Russia approve the tests beforehand, a concession Bush refused to make.

Some Bush advisers played down the exchange, saying it was mentioned only briefly in the talks and was not a major factor.

U.S. officials said there was some disappointment over Putin's insistence that the nuclear cuts be put in writing. Bush doesn't want to do that; he says the leaders can trust each other, and he doesn't want lengthy negotiations to sideline the ABM issue.