The head of Turkey's armed forces has reaffirmed his view that a cross-border operation is needed to fight Kurdish guerrillas based in Iraq.

But General Yasar Buyukanit said Wednesday in a televised news conference that the Turkish government would have to set guidelines for such an incursion.

In April, the general said a cross-border operation against the rebel Kurdistan Workers Party, or PKK, was necessary. Turkey says the rebels are launching attacks on Turkey from Iraq.

A U.S. Defense Department spokesman said Wednesday that Washington understands the threat of terrorism Turkey faces from the PKK, but that the U.S. does not believe a Turkish military excursion into Iraq would be helpful in any way.

Earlier this month, U.S. Secretary of State Condoleezza Rice discussed the issue of the PKK in Iraq with her Iraqi counterpart, Hoshyar Zebari. Rice reaffirmed Washington's determination to clamp down on Kurdish rebels that use northern Iraq as a base for attacks against Turkey.

The PKK has been fighting for autonomy in Turkey's mainly Kurdish southeast since 1984. The violence has killed more than 30,000 people.

The United States, Turkey and the European Union classify the PKK as a terrorist group.

Some information for this report was provided by AP and Reuters.