BAGHDAD (AP) – Kurdish authorities in northern Iraq said Wednesday that their forces would defend civilians if they were caught up in any fighting between Turkish troops and Kurdish rebels from the outlawed PKK in the area.

On Tuesday, Turkey sent hundreds of troops across the border into the frigid mountains of northern Iraq, claiming it inflicted heavy losses on Turkish Kurd rebels in the small-scale incursion, which lasted about 15 hours, and from air strikes two days earlier.

The offensive puts more pressure on Washington to mediate between Iraq and Turkey. In a sign of increasing tension, the U.N. High Commissioner for Refugees reported that more than 1,800 people fled their homes in parts of Iraq’s semiautonomous Kurdistan last weekend.

Iraqi officials have complained that Turkey’s actions are a violation of Iraqi sovereignty, although they have also said they recognize the threat posed by the PKK, or Kurdistan People’s Party.

“We are not part of the military dispute between Turkey and the PKK,” said Jabar Yawar, a spokesman for Kurdistan’s Peshmerga militia.

Yawar said that “if there are any violations by Turkish troops against any secure civilian villages, the Peshmerga will do their job to defend their citizens.”

Tuesday’s raid was the first confirmed Turkish ground operation targeting rebel bases inside Iraq since the U.S. invasion in 2003, though about 1,200 Turkish military monitors have operated in northern Iraq since 1996 with permission from local authorities.

However, the incursion was not a large-scale push that some feared could destabilize a relatively calm part of Iraq, and which is adjacent to the nation’s main northern oil fields around Kirkuk.

In November, the Turkish military reportedly massed 100,000 troops along the border, and there are fears that a major Turkish offensive could cause civilian casualties and lead to conflict with the Peshmerga.

The rebels have battled for autonomy in southeastern Turkey for more than two decades and use strongholds in northern Iraq for cross-border strikes. Turkey has said it can no longer tolerate the attacks on its troops, and in October Turkey’s Parliament authorized the country’s military to strike back at the rebels inside Iraq.

Tuesday’s operation involving about 300 soldiers began about 3 a.m. and lasted 15 hours before the soldiers returned to Turkey, Iraqi Kurd officials said. “Today’s Turkish military operation was a limited one, and the troops withdrew from Iraqi territory,” Yawar said.

The Turkish military issued a statement saying ground forces based close to the border crossed “a few kilometers” into northern Iraq after spotting a group of rebels trying to infiltrate into Turkey overnight. “A heavy blow was inflicted on the group with the land forces stationed in the area,” it said.

The incursion came after Turkey launched airstrikes by as many as 50 Turkish fighter jets Sunday against Kurdish rebel positions in northern Iraq. Iraqi officials said one civilian was killed.

The military said it was not able to give the number of rebels who may have been killed during the airstrikes, but maintained that “many facilities harboring the PKK were hit.”

It was unclear what role the U.S. played, if any, in Tuesday’s ground operation.

U.S. military commanders in Iraq didn’t know Turkey was sending warplanes to bomb in northern Iraq on Sunday until the planes had already crossed the border, said defense and diplomatic officials, who were angered about being left in the dark.

Americans have been providing Turkey with intelligence to go after Kurdish rebels in northern Iraq, and a “coordination center” has been set up in Ankara so Turks, Iraqis and Americans can share information, two officials said Tuesday.

But defense and diplomatic officials in Washington and Baghdad said that U.S. commanders in Iraq knew nothing about Sunday’s attack until it was already under way. They spoke on condition of anonymity because they were not authorized to speak on the record.

The latest ground incursion is small compared with Turkish offensives across the border during the 1990s, when Ankara launched a series of major air and ground attacks against rebel bases. In the most extensive campaign, opened in March 1995, more than 35,000 Turkish troops pushed up to 35 miles (56 kilometers) into Iraqi territory.