Turkey has come under renewed pressure to end its incursion into northern Iraq against a Kurdish rebel group.  U.S. Secretary of Defense Robert Gates visited Ankara and reiterated Washington's call to end the operation, which Turkey says has killed more than 230 rebels in the past week.  Dorian Jones reports from Istanbul.

U.S. Secretary of Defense Robert Gates held a series of talks with Turkey's political leadership and spoke about the incursion after meeting his Turkish counterpart, Vecdi Gonul.

"The United States believes the current operation must be as a short and as precisely targeted as possible," Gates said.

But Gonul was equally firm, saying Turkish forces would remain in Iraq as long as necessary.  Gates said no discussions were held on a specific timetable for the end of the Turkish incursion.  But he ruled out cutting off U.S. support for the operation.  The United States is providing intelligence information on Kurdish rebels to Turkish forces.

Turkey accuses the Kurdistan Workers Party, known as the PKK, of using northern Iraq as a base to launch attacks against its forces.  The rebels have been fighting for autonomy in Turkey's predominantly Kurdish southeast since 1984. 

This latest incursion into Iraq is seen as a pre-emptive strike against an expected spring offensive by the PKK.  But with fighting continuing to intensify, pressure is growing on Turkey to withdraw. 

Washington is anxious to avoid alienating Iraqi Kurds, and Gates urged Ankara to work with the Iraqi-Kurdish leadership.  He also called for a political, as well as a military, solution to the insurgency.

"It should be clear military action alone will not alone end this terrorist threat, while it is certainly part of the equation there must be simultaneous efforts with non military initiative with economic programs and political outreach," Gates said.

But for now, Ankara is determined to follow only a military solution to the PKK threat.  Turkish forces claim to have killed hundreds of rebels and destroyed more than 400 PKK targets.