Turkey launched land and air assaults into neighboring Iraq on Wednesday after Kurdish militants killed at least 24 soldiers and injured 18 in the latest in a series of deadly strikes near the border, authorities said.
The Turkish offensive across the Iraqi border included helicopter gunships, ground commandos and fighter jets, authorities said.
Prime Minister Recep Tayyip Erdogan canceled a foreign trip and labeled the operation a legal "hot pursuit" of terrorists operating out of Iraq's Kurdish region. The overnight attacks were blamed on the PKK, or Kurdistan Workers Party, which has long used mountain bases in rugged northern Iraq to stage guerrilla-style attacks into Turkey, Erdogan said.
The PKK, which seeks what it calls equal rights for Turkey's Kurdish minority, and Ankara have been locked in a decades-long struggle that has left tens of thousands dead and has recently heated up anew. Public anger in Turkey about the escalating violence has been mounting, putting pressure on Erdogan and other leaders for a robust response.
"Those who think they can subjugate us through such heinous assaults are bound to realize that we will take our revenge," declared Turkish President Abdullah Gul. "These terrorist acts will be reciprocated."
In recent months, Turkish authorities say, PKK militants have killed dozens of security personnel and civilians inside Turkey's embattled Kurdish heartland. Turkey has already launched a security crackdown, but Erdogan has been hinting that Ankara would strike back even harder.
The offensive Wednesday was believed to be Turkey's largest cross-border ground operation into Iraqi territory since a 2008 onslaught against the PKK.
It remained unclear how far Turkish troops planned to advance inside Iraq, and how long forces would remain. Reuters news agency cited sources as saying that about 500 Turkish troops had moved up to five miles into Iraqi territory.
The Turkish attack did not appear to be as massive as the 2008 incursion, which was said to have involved as many as 10,000 Turkish troops.
Turkey and its allies, including Washington and the European Union, have labeled the PKK a terrorist group. The U.S. ambassador in Ankara denounced the latest PKK attacks, as did the North Atlantic Treaty Organization, which includes Turkey among its members.
Massoud Barzani, the president of Iraqi Kurdistan, condemned the Turkish raids as a "criminal act," Reuters reported.
Iraq's Kurdish power structure, with close ties to Washington, controls the autonomous Kurdish region in northern Iraq. Barzani and other Iraqi Kurdish leaders navigate between public sympathy for their Turkish kinsmen and a disinclination to alienate Turkey, a regional powerhouse.
Ethnic Kurds are a significant minority throughout the region and have also complained of second-class status in Iran and Syria.
Officials in Washington have long worried that the Turkish-PKK struggle could heighten instability in Iraq as U.S. troops pull out of the country. American forces led the 2003 invasion that ousted Saddam Hussein and are scheduled to leave Iraq at the end of this year.