President Bush, expressing growing impatience, appears grimly determined to show he is willing to go to war against Iraq to end its takeover of Kuwait.

The resounding message of Bush's just-concluded trip through Europe and the Middle East was that time is running out for a peaceful retreat by Iraqi President Saddam Hussein.For the first time, Bush raised the possibility of setting a deadline for Baghdad.

He also spoke bluntly of "a commitment to use force." And he offered a chilling justification for amassing military forces against Iraq, warning that Saddam was moving closer to building an arsenal of nuclear weapons.

"The world is getting tired of this," Bush declared of Iraq's nearly four-month occupation of Kuwait.

Bush's theme was that he hopes for a peaceful resolution but is laying the foundation for possible war. He said he was not bluffing.

Prodded by the United States, the U.N. Security Council is expected to meet within days on a measure authorizing force to remove Iraq.

Bush said the United States is very close to winning U.N. approval. Even without it, he said, "We have the authority to do what we have to do."

Congress was uneasy about Bush's saber-rattling before his trip, and the hardening of his rhetoric is sure to raise new concerns.

Senate Minority Leader Bob Dole of Kansas said he would urge Congress to reconvene immediately if the United Nations endorsed a resolution on force. He said he hoped Congress also would endorse force.

Bush made the Persian Gulf crisis the constant centerpiece of his eight-day trip to Czechoslovakia, Germany, a 34-nation summit in Paris, Saudi Arabia and Egypt.

"We're not walking away until our mission is done, until the invader is out of Kuwait," Bush told Marines and British "Desert Rats" during a Thanksgiving Day visit to a remote desert outpost in Saudi Arabia. "And that may be where you come in."

The 230,000 American troops in the Persian Gulf, and 200,000 more on the way, give real credence to the president's implied threat.

Yet, despite Bush's resolve, there are signs of wear in the global coalition against Iraq and there is reluctance - or mixed signals - from some nations about the military option.

Soviet President Mikhail S. Gorbachev counseled patience to allow diplomacy to work. So did German Chancellor Helmut Kohl, warning of the consequences of war.

On the other hand, Margaret Thatcher ordered 14,000 more British troops to the gulf even as she announced her resignation as prime minister.

Bush got public backing from Egypt and Saudi Arabia for using force, and Syria agreed that Iraq's aggression must not stand. However, there were divisions in the Arab world.

Yemen, which will assume the rotating chairmanship of the Security Council in December, criticized the military buildup in the gulf and refused to endorse tougher action.

Yemen's attitude is a key reason why Bush wants U.N. action before the end of the month when the United States has to relinquish the council chairmanship.

Secretary of State James A. Baker III, who has circled the globe in recent days lobbying for tougher action, cautioned against "the siren song of partial solutions."

And Baker said disapprovingly that some nations are beginning to talk of allowing Iraq to hold on to disputed islands in the gulf or be granted access to the gulf.

"So-called partial solutions are out of the question," Bush declared.

Stopping in Cairo, Bush vowed, "We're going to pull this coalition together. We're going to keep this coalition together and we're going to see what happens."

Egyptian President Hosni Mubarak, known for his caution, spoke gloomily about prospects for a peaceful ending. "I am pessimistic," he said. "I don't see the slightest movement" by Saddam.

If he needed it, Bush got encouragement for quick action from some of the American troops he visited in Saudi Arabia and aboard the amphibious assault ship USS Nassau in the Persian Gulf.

"We either want to fight or we want to go home," said Marine Lance Cpl. David Kimmel of Jonestown, Pa.

"I wish it would happen because I'm tired of being here," agreed Lance Cpl. Doug Mitchell of Hattiesburg, Miss.

Troy Knapp, a 19-year-old corporal from Denver, said he thought Bush was looking for a military solution. "You're going to wonder if he'll take the political heat for keeping the troops here for another five months," Knapp said.

Bush told the troops: "No American will be kept in the gulf a single day longer than necessary, but we won't pull punches. We are not here on some exercise. This is a real world situation."

Bush has refused to specify how long he'll wait for sanctions to work against Iraq. But he said that at the United Nations, "We'll be discussing not only the need to consider further action, but perhaps a time frame."