LONDON, JAN. 6 -- Secretary of State James A. Baker III took a firm line today against new diplomatic initiatives in the Persian Gulf crisis, rejecting a French peace proposal, further United Nations diplomacy or a personal mission to Baghdad, and announced he will begin consulting allies in the anti-Iraq coalition about the decision to go to war.

Baker acknowledged that some of the nations that have sent troops to the Arabian Peninsula may not be committed to actual combat. While some nations "are eager to fight," Baker said, "there are some varying degrees of commitment." Baker said the question of who will fight to expel Iraq from Kuwait -- and when -- will be a major topic of discussion on the nine-nation, eight-day tour to Europe and the Middle East he began today.

The centerpiece of that tour is a meeting Wednesday with Iraqi Foreign Minister Tariq Aziz in Geneva, and Baker emphasized again that he is going into the session only to deliver the international coalition's message that Iraq must vacate Kuwait. Baker disclosed that on Saturday he held his first conversation with Soviet Foreign Minister Eduard Shevardnadze since the Soviet minister announced his resignation last month, and Baker indicated that Moscow is sending a similarly firm message to Iraq.

In Baghdad, Iraqi President Saddam Hussein warned Iraqis in a speech to prepare for a "battle against the tyranny represented by the United States" that he said would require "serious sacrifices" by his country, signaling no willingness to withdraw from Kuwait or make concessions to resolve the gulf crisis peacefully. {Details, Page A22.}

The hard line taken by Saddam and Baker reflected the war of nerves being played out by both sides in advance of the Aziz meeting. Baker said the United States was "discouraging any divergent messages" in advance of the first high-level contact with Iraq since the Aug. 2 invasion of Kuwait.

Baker is carrying a letter from President Bush stressing the resolution of the alliance to go to war if necessary and he hinted that he has prepared a stark presentation to Aziz that will be convincing of the power of the alliance to destroy Iraq in war, Baker but would not provide details. He said the administration believes Saddam has been trying to forestall any military action against him. Baker added, "I think there very well might be" a new surprise proposal from Saddam as the Jan. 15 U.N. deadline approaches.

Baker said he is not optimistic that his meeting with Aziz will result in progress toward a diplomatic solution of the five-month-old confrontation. Baker expressed exasperation at what he described as repeated efforts by Iraq to avoid meeting the demands of the international community. He said if the United States agreed to further talks or negotiations now, Saddam would try to drag them out beyond the U.N. deadline and into the spring.

He said the alliance has been "patient" over the last five months and "we have got to get the message through to them that this is the last" chance.

Baker said his central message is, "If they comply with all the United Nations resolutions and withdraw from Kuwait, they can expect force will not be used against them, and if they refuse to do that, they must face the fact that in all probability force will be used to require them to do that."

Baker threw cold water on a French peace proposal, advocated by President Francois Mitterrand, that calls for a complete Iraqi withdrawal from Kuwait but envisions an international peace conference on the Middle East. Saddam repeatedly has demanded that talks on regional issues, including the Israeli-Palestinian conflict, be held if Iraq is to withdraw.

The United States has said it may accept such a conference at an "appropriate time" but not with any "linkage" to the Iraqi occupation of Kuwait. Asked if the Mitterrand plan was such linkage, Baker said, "Yes," and added, "We would find it impossible to sign onto it."

The secretary also gave the back of his hand to any possible diplomatic efforts by the U.N. Security Council. Noting the series of resolutions passed by the council calling for Iraq to surrender Kuwait, he said, "It's hard to see what any further Security Council meeting" could accomplish.

Baker was questioned repeatedly today, in speaking to reporters en route here and in an appearance on the ABC News "This Week with David Brinkley," about Bush's announcement Friday that Baker could not go on to Baghdad to see Saddam after his talks with Aziz. There has been speculation that the Geneva meeting could be a prelude to such a trip.

Baker, attributing the decision to the president, reiterated "that there will be no meeting in Baghdad." But under questioning he refused to rule out any kind of meeting with Saddam in a neutral country.

"The president said there will be no meeting in Baghdad," Baker said. "I'll leave it right there."

Asked earlier on the television broadcast if he was not closing the door to high-level talks after the Geneva session, Baker said, "I am closing the door."

Bush administration officials, in a coordinated round of televised interviews, portrayed Baker's meeting with Aziz as the final effort to secure Iraq's peaceful removal from Kuwait.

"We're making one last attempt" to convince Saddam that "he faces certain use of force to get him out of Kuwait if he will not do so voluntarily," said national security adviser Brent Scowcroft, interviewed on CNN's "Newsmaker Sunday."

Voicing skepticism that diplomacy will wrest Kuwait from Iraqi control, Scowcroft and Defense Secretary Richard B. Cheney brushed aside initiatives by the European Community, the Nonaligned Movement and the Arab world.

Cheney, on CBS's "Face the Nation," described a report in Sunday's Washington Post, in which a senior administration official said the United States would accept any agreement reached among Iraq, Saudi Arabia and Kuwait, as "a misstatement of the situation." Reviving allusions to the rise of Adolf Hitler in the 1930s, he said any compromise settlement would be "appeasement."

Scowcroft said he saw no prospect of a diplomatic breakthrough by "would-be mediators, well-wishers and so on" from the Middle East and Europe.

But Indiana Sen. Richard Lugar, a senior Republican on the Foreign Relations Committee, diverged from the administration line by endorsing the Arab world's diplomatic efforts.

"I think there's going to be a lot of diplomacy in the next nine days," Lugar said on NBC's "Meet the Press." "The Arab League situation looks particularly promising, I suppose. And, clearly, if Kuwait and the Saudis and Iraq move off to some agreement over there, it's likely to be one we might support."

Baker said his presentation to Aziz would include the pledge not to attack Iraqi troops if they retreat from Kuwait, but he said even with a complete withdrawal there would have to be restrictions on arms flowing into Iraq. Baker said he did not think he could talk about the future peace process in the Middle East without getting tangled into "linkage."

Baker was not specific about what kinds of discussions he intended to have with the allies about going to war. The decision to use force has "not been made," he said, "but part of my job on the trip is to talk about next steps and talk about what plans, what the state of the planning is, and is not, and get into issues like that." In the past, he has said a decision to fight would have to be made at the highest political levels.

Baker's itinerary includes meetings in Britain, France, Germany, Switzerland, Turkey, Saudi Arabia, the United Arab Emirates, Egypt and Canada. Although Baker did not identify which nations were eager to fight and which were not, the Saudis, the small gulf states and Britain are generally regarded as among those most willing. France and some other countries, including Syria, have deployed troops but have emphasized the importance of trying to avoid conflict that could inflame the entire region.

Baker pointedly refused to discuss what actions the United States might take immediately after the Jan. 15 deadline if Iraq ignores it. He said he could not discuss, for example, whether the United States will seek to evacuate its embassy in Baghdad after that date.

Although Baker also refused to divulge details about Bush's letter to Saddam, a senior official traveling on his plane suggested it would be made public later. "On this meeting, there isn't going to be any secret diplomacy," the official said. "You'll know in due course what we say and how we say it."

Staff writer Barton Gellman in Washington contributed to this story.