Turkey's incursion against Kurdish rebels in northern Iraq should be short and focused, U.S. Defense Secretary Robert Gates said Thursday. But Turkey's military chief declined to set a timetable for the withdrawal of troops, who have been operating in Iraq for a week.

"The United States believes the current offensive should be as short and precisely targeted as possible," Gates said after a meeting with Turkish counterpart Vecdi Gonul.

Gen. Yasar Buyukanit said he told Gates in a meeting later that Turkey's fight against the rebels was long-term, and that the defense secretary reacted with "understanding" to his remark.

"Short term is a relative notion. Sometimes it is a day, sometimes it is a year," NTV and CNN-Turk television news stations quoted Buyukanit as saying. "We have been struggling against terrorism for 24 years. That is why our struggle against terrorism will continue. The United States is also struggling against terrorism. It has been in Afghanistan for years."

Prime Minister Recep Tayyip Erdogan told Gates that "Turkish soldiers would return after achieving goals," the state-run Anatolia news agency reported.

The U.S.-backed Iraqi government has demanded an immediate end to the operation, which began Feb. 21. Gates has said the cross-border assault must not last longer than a week or two.

"Turkey's government should make clear to the Iraqi government and everyone concerned exactly what their intentions are and the limited goals and scope of their operations," Gates said. "I believe there is a growing appreciation of the complexity of the situation of balancing the right of Turkey to defend itself with the need to maintaining Iraqi sovereignty and territorial integrity."

Gonul said Turkey would end its operation after reaching its goals.

"It depends on winter conditions. If the mission is accomplished, we have no intention of staying there," Gonul said.

Gates called on Turkey to address the economic and social concerns of its Kurdish minority, which complains of cultural and other restrictions as well as deep poverty in many areas. Kurdish rebels seek autonomy for the predominantly Kurdish southeast of Turkey, and took up arms against the Turkish state in 1984.

"Military action alone will not end this terrorist threat. Simultaneous efforts should be made with nonmilitary initiatives," Gates said. "Economic programs and political outreach. That is the only way to isolate terrorists from the population and provide a long-term solution to the problem."

He urged Turkey to engage in dialogue with Iraqi and Iraqi Kurdish leaders. Turkey has long suspected the Iraqi Kurd administration in the north of allowing the Kurdistan Workers' Party, or PKK, to operate and ignoring calls for a crackdown on the group.

"The key for all parties is transparency, cooperation and communication," Gates said.

Gates said "a specific timetable did not come up" for withdrawal during his meeting with Gonul.

Gates ruled out any threat to halt the sharing of intelligence about rebel positions if Turkey did not withdraw.

"We have shared interests here," he said. "I think that those interests are probably not advanced by making threats or threatening to cut off intelligence."

Turkish artillery units fired shells across the Iraqi border and helicopters streamed toward Iraq from the border town of Cukurca, according to an Associated Press photographer at the scene.

Gonul said there were no civilians in the areas where Turkish soldiers were conducting their operations.

"We have no intention of disturbing any civilian area. We have no intention of interfering in domestic politics and we have no intention of occupying any area," Gonul said.

Turkey's military has said it has killed 230 rebels in the operation while Turkish losses stood at 27. The remote battle sites are inaccessible to the media and casualty reports cannot be independently confirmed.

It is the first confirmed Turkish military ground operation in Iraq in about a decade. The rebels have carried out attacks from northern Iraq. The conflict has killed up to 40,000 people since 1984. The U.S. and EU consider the PKK to be a terrorist group.