Buses of U.N. relief workers left the Iraqi capital before dawn Thursday - getting out of the way of a threatened U.S. attack in case U.N. Secretary-General Kofi Annan's peace mission to Baghdad fails.

The Polish Embassy, which has represented U.S. interests in Baghdad since the gulf war, evacuated 10 of its 16 diplomats as well. The Polish ambassador and another diplomat who works on behalf of the United States were among those staying behind.U.S. preparations for conflict intensified, with 250 infantry soldiers arriving Thursday in Kuwait - the first contingent of a 3,000-strong ground force to defend Iraq's smaller neighbor from any retaliation against a U.S. attack.

The Fort Stewart, Ga.-based troops join 25,000 U.S. servicemen and women already in the gulf region.

Annan flew out of New York Thursday to start his peace mission, which will take him to talks in Paris and then on to Iraq, where he is to meet with Iraqi leader Saddam Hussein.

Annan, who won the U.N. Security Council's blessing Wednesday for the trip, said he was "reasonably optimistic" for a diplomatic solution to the crisis over U.N. weapons inspections in Iraq.

The trip has been seen as a last chance to avert a threatened U.S.-led attack to force Saddam to open eight presidential sites to inspections by U.N. weapons experts.

Saddam sent a message to Russian President Boris Yeltsin saying he remains committed to a negotiated solution, the official Iraqi News Agency reported. Yeltsin has been one of the loudest opponents to any use of force to end the standoff.

Despite Annan's optimistic talk, 29 U.N. employees loaded their gear into buses in Baghdad Thursday and headed to safety in Amman, Jordan. Denis Halliday, the U.N. humanitarian coordinator for Iraq, said roughly the same number would leave Friday. Two other employees were going to Kurdish-controlled northern Iraq.

Last week, the world body ordered 81 staff members on leave abroad not to come back to Iraq.

About 250 humanitarian workers from a total staff of 400 remain in Iraq to run the U.N.-approved oil-for-food program distributing aid to Iraqis, but Halliday said the withdrawal "clearly diminishes our capacity."

"We told people, based on the decision in New York, that we needed to reduce the staff temporarily until hopefully we get a diplomatic solution," he said. "We hope to see them back shortly."

On Wednesday, a three-man team finished mapping the presidential palaces at the center of the U.N.-Iraq dispute. The team is determining the size of the presidential compounds and how many buildings they contain to help define which buildings U.N. weapons inspectors want to examine. (See story at right.)