Around 250 Polish soldiers have left for Kuwait to begin preparations for a multinational peacekeeping force in central Iraq.
Poland is sending 2,300 troops to the sector
Poland, a staunch European ally of the United States, will take command of more than 9,000 troops from 15 nations - including 2,300 of its own - when the force is ready at the beginning of September.
Poland was given command of the sector, which is sandwiched between the US and British sectors, after a small group of its troops fought in the war against Iraq.
It is the first time Poland has led such a large multinational peacekeeping force.
Faced with a worsening security situation in Iraq, the troops are aware their mission will be difficult.
"We know there are risks and we are ready to assume them," said Chief of Staff General Czeslaw Piatas.
Defence Minister Jerzy Szmajdzinski said Polish officers were analysing attacks on US and British troops to find ways of dealing with the dangers involved.
Opinion polls suggest that Poles are as sceptical as Western Europeans about military efforts in Iraq, despite strong backing for the US-led operation from mainstream politicians.
BBC world affairs correspondent William Horsley says well over 20 countries overall could provide some level of help for the force.
The Dutch Defence Ministry announced it had sent 25 military engineers, the first of 1,100 troops who will serve in the British sector.
And Ukraine military officials said 1,800 troops would be deployed under Polish command by September.
Other contributing nations are thought to include Spain, Hungary, Slovakia, Lithuania, Honduras, El Salvador and the Dominican Republic.
US Defence Secretary Donald Rumsfeld says he wants to see as many troops from other nations as possible to give US forces a rest and gradually reduce their numbers.
But our correspondent says the challenge is immense, and such a diverse force has never been put together before without the formal command of either the UN or Nato.