An Iraqi fighter pilot flew deep into the southern no-fly zone Saturday

WASHINGTON (CNN) -- An Iraqi fighter plane violated a no-fly zone on Saturday, flying deep into the western part of restricted airspace near Saudi Arabia, Pentagon sources said Monday.

There were no coalition aircraft in the area at the time, and there was no confrontation. The Pentagon said the violation was not "militarily significant."

U.S., British and French warplanes began enforcing two no-fly zones over Iraq after the 1991 Gulf War to stop Iraq from using its air force against Kurdish rebels in northern Iraq and Shiite Muslims in the south.

Iraq has tested the southern no-fly zone repeatedly, especially in recent days, with fighter planes and helicopters. Despite the violations, the no-fly zones have been 100 percent effective in protecting Iraqi minorities, military sources told CNN.

The sources said coalition forces are not stalking or waiting to ambush Iraqi planes in the no-fly zone. But they said if Iraqi aircraft or surface-to-air missile batteries threaten coalition planes, they reserve the right to attack and destroy them.