US President George W Bush is asking Congress for $400m (£215m) to reward a number of countries that sent troops to Afghanistan and Iraq.
Poland has been one of the US's staunch allies in Iraq
A White House spokesman said the money would "assist nations which have taken political and economic risks".
The fund is part of a $80bn war funding request President Bush will send to Congress next week.
It is thought the money could prove an incentive for countries to stay in Iraq. Several nations have withdrawn.
Poland, for instance, which has 2,500 troops in Iraq, will receive $100m.
Mr Bush announced the Polish donation during a meeting with Polish President Aleksander Kwasniewski.
"Poland has been a fantastic ally because the president and the people of Poland love freedom," Mr Bush said.
"I know the people of your country must have been thrilled when the millions of people went to the polls" in Iraq, he added.
The fund, called the Solidarity Initiative, will benefit countries "promoting freedom around the world", White House press secretary Scott McClellan said in a statement.
"These funds... reflect the principle that an investment in a partner in freedom today will help ensure that America will stand united with stronger partners in the future," he added.
Officials declined to say which other nations would benefit, but there has been a suggestion that the fund will provide help to eastern European nations such as Ukraine, Hungary, Romania and the Baltic states.
It could also be used as an incentive not to leave the coalition in Iraq. Spain, Singapore, Nicaragua, New Zealand, Thailand, the Philippines, Norway and Honduras have all pulled out.
Democratic Sen Joseph Biden of Delaware, the ranking minority member of the Senate Foreign Relations Committee, said the plan was indicative of the administration's inability to attract more well-to-do nations to the coalition at the start of the conflict.
"It's kind of a shame," he told the Associated Press news agency.
"The reason we're having to do this is that we never reached out to those who have the ability and capacity to do this to begin with," he said.