Slovak Premier Robert Fico used a news conference with NATO Secretary-General Anders Fogh Rasmussen to say: "We opposed the mission in Iraq because the use of military force was only motivated by oil."
Meetings of NATO defense ministers are rarely adversarial, and even if differences emerge these are handled by diplomats who almost never allow them to become public.
The administration of President George W. Bush explained the U.S.-led attack on Iraq by the urgent need to destroy Saddam Hussein's arsenal of weapons of mass destruction, but no such weapons were ever found. Nearly 100,000 people have died in the conflict since then, according to Iraqi government statistics.
A number of European allies, such as France and Germany, refused to join in the invasion and the subsequent occupation in which NATO as an alliance was not involved. But others, including Poland and Holland, dispatched units to join the "coalition of the willing."
"Slovakia is willing to cooperate if there is a legitimate goal, such as the fight against terrorism ... where there is international blessing for it," he said.
Fico also said Thursday he would not allow any part of a revamped U.S. missile shield planned in Europe to be based in Slovakia, if he were ever approached.
Fogh Rasmussen did not say anything in response to Fico's comments.