As reported by Juan Cole and by the Lebanese paper, the Daily Star:
Turkish Prime Minister Recep Tayyip Erdogan has again warned he could take action against Kurdish guerrillas in Iraq if U.S. forces did not stop the rebels infiltrating across the border into Turkey. "At the moment, frankly speaking, we do not see the efforts by the U.S. that we expect to see. We have expressed our views to that effect to the Americans," Erdogan said in an interview yesterday with Britain's Times newspaper. "There is a time limit. There is a limit to our tolerance," said Erdogan.
He said Turkey was within its rights under international law to defend itself from attack and drew a comparison with U.S. action against Afghanistan after the September 11, 2001 attacks.
http://www.dailystar.com.lb/article.asp?edition_id=10&categ_id=2&article_id=17177
Read the whole thing at the link above.
I remember that there were some who warned that this may happen prior to the US invasion of Iraq. They warned that there would be an Iraqi civil war, which some are saying is now beginning, and that the Kurds would agitate and cause problems, if not an invasion by the Turks of Iraq.
I also remember these same people warning that the Shiites in Iraq would cozy up to Iran, which we have all read in the newspapers.
My point? I guess they were right.