DHAHRAN, SAUDI ARABIA, NOV. 22 -- President Bush, sharing Thanksgiving with U.S. forces in the Persian Gulf, warned today that Iraq may be close to acquiring nuclear weapons and pledged that "we won't pull punches" in seeking to force the Iraqi army out of Kuwait.

Bush said "nobody can know" with certainty how close Iraqi President Saddam Hussein is to acquiring nuclear arms. "But this I know for sure. He's never possessed a weapon he did not use," the president told about 1,500 U.S. Marines, members of Britain's Desert Rats armored brigade and U.S. Navy Seabees camped in the desert 65 miles from the Kuwaiti border.

Most Western experts estimate Iraq is still five to 10 years away from being able to produce a small arsenal of nuclear weapons, while a few, including some Israelis, have said Iraq could have such weapons in two years or less.

Bush, invoking Iraq's nuclear potential for the first time as a key reason for confronting Baghdad, said: "Those who would measure the timetable for Saddam's atomic program in years may be seriously underestimating the reality of that situation and the gravity of the threat." With every passing day, Bush said, Saddam is "one step closer to realizing his goal of a nuclear weapons arsenal. And that's why, more and more, your mission is marked by a real sense of urgency."

But while Bush spoke forcefully about the Iraqi threat and the possibility that U.S. troops might have to resort to force, the commander of U.S. forces here, Gen. Norman Schwarzkopf, warned in an interview with CBS News that U.S. troops are not yet ready to attack Iraq.

Asked by CBS anchorman Dan Rather if he was prepared to go on the offensive if ordered, the general said: "No, I don't think so. I think we need the additional troops before we go on the offense," referring to the 200,000 fresh troops recently ordered to the region to double the size of the force already in place. "I think that first of all we have to wait and see if the sanctions work. . . . Nobody wants to rush into war," Schwarzkopf said.

Bush emphasized Saddam's nuclear capability during a Thanksgiving tour on which the president paid tribute to U.S. troops as "a proud force for freedom." Bush, dressed in a blue work shirt, khaki slacks and desert boots, crisscrossed the desert in his Marine One helicopter and spoke briefly with men and women of all the armed services at an air base in Dhahran, two desert encampments and aboard the USS Nassau, an amphibious assault ship in the Persian Gulf on which he and members of his entourage attended religious services.

With his wife, Barbara, at his side, Bush gulped down Thanksgiving dinner at two of the stops. Between bites, he stood signing autographs, shaking hands and cheering on some of the 230,000 Americans called here to serve in Operation Desert Shield. The U.S. troops make up the overwhelming majority of an international force deployed in the gulf region following Iraq's Aug. 2 invasion of Kuwait.

By day's end, the president's attacks on Saddam grew stronger, his warnings more sharp, the sense that combat may lie ahead more real, his response from the troops more enthusiastic.

"More and more, your mission is marked by a real sense of urgency," the president told U.S. Army troops. "We won't pull punches. We are not here on some exercise."

To Marines at a desert outpost in eastern Saudi Arabia, Bush described Saddam as "a classic bully who thinks he can get away with kicking sand in the face of the world." At each stop he drew roars of approval for such exhortations as: "We're not here on some exercise. This is the real world situation and we're not walking away until our mission is done, until the invader is out of Kuwait. And that may well be where you come in."

"There are times when all nations that value freedom must confront aggression," Bush told the troops at one outpost. "Sometimes it's a question of some pain now to avoid even worse pain later."

As Bush was turning up the verbal pressure on Saddam before flying to Cairo for meetings with Egyptian President Hosni Mubarak, Secretary of State James A. Baker III was in Yemen continuing consultations concerning a possible United Nations resolution that would authorize the use of military force against Iraq. At the same time, Soviet Foreign Minister Eduard Shevardnadze was en route to China to meet with officials there as part of the backstage diplomacy aimed at reaching agreement by the end of the month on the wording of the resolution.

Bush praised the participation of British forces in the gulf on a day when his staunchest ally, Prime Minister Margaret Thatcher, resigned and British Defense Minister Tom King, perhaps to emphasize the continuity of Britain's commitment, announced that London was sending 14,000 more troops and more combat aircraft to bring the total British force to 30,000.

Bush was accompanied on his tour by Schwarzkopf, national security adviser Brent Scowcroft and congressional leaders, who expressed broad support for the president's actions thus far in the gulf but repeated their calls for consultations with Congress if he decides to seek military action.

House Speaker Thomas Foley (D-Wash.) said the policy "as it is presently stated is the policy of deterrence and restraint, and that has very broad support." But House Minority Leader Robert Michel (R-Ill.) expressed some concern about keeping so many troops deployed for a lengthy period, perhaps a year. "I think you can't delay it forever," he said. Senate Majority Leader George Mitchell (D-Maine) and Minority Leader Robert Dole (R-Kan.) also accompanied the president.

Bush spoke to about 5,000 soldiers and seamen and seemed to hear fewer complaints of boredom, anxiety over the future and disgust with conditions than Baker and other VIP visitors had heard here.

Most took the president's appearance on this holiday as an affirmation of American support. "It makes me feel he at least took the time to come and see us and that he cares," said Sgt. Clyde L. Williams, of Forestville, Md.

Many, however, were hoping to hear from Bush on when -- or whether -- they would be sent into combat or sent home.

Sgt. Timson Carrier, of Eunice, La., said it "meant a lot to me that the president is here when he could be home with his family." Asked what he wanted to hear from Bush, he replied: "I want to hear him say this is all over with and let's go home."

"It will give us all something to talk about for a few days, then it will be forgotten," Air Force Sgt. Mark Johnstone of Hampton, Va., told the Reuter news agency. "It's hard to keep morale up when all you do is wait. It's like being in the hospital."

Reuter reported that while many soldiers responded to Bush's words with enthusiastic applause, others kept their hands in their pockets. Bush later said he understood that "the waiting is the difficult part of this." The troops "want to do it and do it fast."

Recalling his own feelings on a Thanksgiving Day 46 years ago, when he was a Navy pilot in the Pacific during World War II, Bush said he understood the impatience and would give peace "time" but added it was also time for Saddam to withdraw from Kuwait.

At all four stops on his tour, Bush, his voice sometimes quiet with emotion, offered the nation's thanks and his explanation to the troops for why they were here. "Today, the worldwide march of freedom is threatened by a man hellbent on gaining a choke-hold on the world's economic lifeline," he said, adding, "Energy security is national security."

While the day with the troops had the immediate purpose of bolstering morale, it was also meant to bring home to America Bush's explanations for the stand against Saddam. Public opinion polls show, and the president has agreed, that he has not been fully successful in detailing the reasons for the massive buildup and the U.S. stake in a possible military confrontation. Lately he has broadened his rationale for the U.S. presence in the gulf, including recent statements linking recession in the United States to Saddam's disruption of world oil markets.

Polls last week by the New York Times and the Los Angeles Times also showed that preventing Saddam from obtaining nuclear weapons was the most compelling reason Americans found for taking military action. Asked today if there was new information to cause him to cite the nuclear threat, Bush would only cite his growing concern.

White House Press Secretary Marlin Fitzwater called the day "spectacular" for Bush because of the insight the president gained into the mood of the troops and their situation.

"He was really moved by talking to these guys personally. He could really read their faces," Fitzwater said.