President Bush told a crowd that filled historic Wenceslas Square in Prague, Czechoslovakia, on Saturday that "America will stand with you" through hard times ahead, and he urged European solidarity in the Persian Gulf crisis.

Speaking on the anniversary of the revolution that ended decades of communist rule in Czechoslovakia, Bush likened last year's struggle of emerging democracies against totalitarianism to the current U.S.-led effort to drive Saddam Hussein from Kuwait."The darkness in the desert sky cannot stand against the way of light," Bush said, addressing about 100,000 people who packed the half-mile long, 200-foot wide "square" that is the scene of much recent Czech history.

The first U.S. president ever to visit this central European nation, Bush shared the platform with playwright-president Vaclav Havel. Those in the crowd waved small U.S. and Czech flags and many chanted "Bush, Havel. Bush, Havel."

Meanwhile, U.S. and Saudi troops, backed by more than 1,000 warplanes, prepared Saturday for a mock invasion near the Kuwaiti border. A top Iraqi general warned the U.S.-led force that his army has a "surprise" up its sleeve.

Imminent Thunder, as the current six-day exercises in the gulf are named, is being supported by about 1,100 aircraft, the largest force of warplanes yet assembled for a Desert Shield exercise.

The drill is meant to emphasize gaining control of the skies, which would be critical to smash Iraqi defenses.

Baghdad has called Imminent Thunder a "provocative act" because of its proximity to Kuwait, which Iraq invaded Aug. 2. News reports have said part of the maneuvers could come within 10 miles of the Iraqi-Kuwaiti border.

No live ammunition will be fired, officials say.

The actual landing from amphibious landing craft and helicopters was set for Sunday. It was to involve 1,000 troops from the 4th Marine Expeditionary Battalion.

Maj. Gen. Mundhir Abdul-Rahman, a missile expert and head of the Iraqi army's morale department, did not say what the "surprise elements" were. But he said they would thwart an offensive. His comments were published in Al-Qadissiya, the army's daily newspaper.

It was difficult to determine whether the general was speaking in his capacity as a specialist in long-range weaponry or as chief military morale booster.

After their speeches, Bush and Havel stepped out from their bulletproof enclosure and climbed a wooden platform and joined a folk band that sang "We Shall Overcome," first in English and then in Czech.

Many in the crowd joined in, filling the cold and overcast late afternoon sky with the traditional song that was both a protest anthem for the U.S. civil rights movements of the 1960s and for Czech students in street protests here against communist rule.

A year ago, the square was similarly filled with hundreds of thousands of citizens to begin the so-called "Velvet Revolution" that drove communists from power with little bloodshed.

"The world will never forget what happened here in this square where the history of freedom was written," Bush said.

He praised Czechoslovakia as "one of the first nations to condemn the outrage in the Persian Gulf."

Havel reiterated this view and promised Bush continued support during a joint news conference outside the Hradcany Castle, the Czech equivalent of the White House.

Havel shrugged off a question on whether he was concerned that the Persian Gulf crisis was draining away money that could have been used to help support his country's ailing economy.

"It is my opinion that all the resources that are expended on resisting aggression anywhere in the world are finally turned to the good of all mankind," he said.

Bush was expected to try to further coordinate allied support in Germany on Sunday, where he visits Chancellor Helmut Kohl, and in Paris where he attends a three-day European summit.

Both in his Wenceslas Square speech and in an earlier address to the Federal Assembly, the nation's parliament, Bush offered hope of new U.S. economic assistance to the fledgling democracy.

Earlier, he said final agreement was reached Saturday granting Czechoslovakia most-favored-nation trade status, permitting it to deal with the United States at the lowest possible tariffs and import fee rates.

Bush said he also would ask Congress for $60 million to create a fund to spur U.S. investment here. Moreover, Bush said funds to help build the private sector would be drawn from the $370 million already committed for Central and Eastern Europe for the coming year.

The two leaders were wrapped in heavy topcoats against the biting wind in Wenceslas Square. Earlier, Bush and his wife, Barbara, emerged from Air Force One to a full-fledged state welcome, including a 21-gun salute as flags of both nations snapped in the wind.

Bush was to spend Thanksgiving with U.S. forces in the Persian Gulf region and then end his eight-day trip next Friday with a visit to Egypt for talks on the showdown with Iraq.

Bush meets separately on Tuesday in Paris with Soviet President Mikhail Gorbachev.

In related developments:

- Iraq denied Saturday that it has reversed its position on the crisis, contrary to reports Baghdad was backing away from its rejection of a pullout from Kuwait. "There is no change in our position," Information Minister Latif Nassif Jassem told a news conference, answering a questioner who suggested Iraq might be prepared to move out of Kuwait.

- U.N. Secretary-General Javier Perez de Cuellar struck a gloomy note over the crisis Saturday, saying that an Arab summit appeared to offer the only chance of a peaceful outcome. "So far, I was unable to see any peaceful option, which I very much regret," he told reporters after attending a UNESCO seminar in Paris on how to help poor countries hit by Iraq's invasion of Kuwait.

- About 180 Americans are expected to leave Kuwait for Baghdad and then fly to London Sunday, British Embassy sources in the Iraqi capital said Saturday. They said the Americans, mainly women and children, would fly from Kuwait to Baghdad on two U.S.-chartered Iraqi Airways planes and would later board an Iraqi Airways Boeing 747 flight bound for London. They would be joined by a few Britons from Baghdad.

- Secretary of State James Baker met in Geneva Saturday with the foreign ministers of three non-aligned temporary members of the U.N. Security Council, seeking their support for a possible resolution sanctioning the use of force against Iraq. Approval by Ethiopia, Ivory Coast and Zaire would signal the coalition against Baghdad was firm and united, analysts said.