But how deeply into Iraq is the Turkish army willing to go, how long would it stay and what kind of fallout could come from allies in Washington and other Nato partners?

All these questions weigh on Turkey's leaders, who have enough on their hands without embarking on a foreign military adventure. Turkey is caught up in an internal rift between the Islamic-rooted government and the military-backed, secular establishment, less than two weeks ahead of July 22 elections that were called early as a way to ease tensions in a polarised society.

A military operation could disrupt Turkey's fragile democratic process by diverting attention from campaign topics such as the economy, and raise suspicion about whether the government and its opponents are manipulating the Iraq issue to win nationalist support at the polls.

On Monday, Prime Minister Recep Tayyip Erdogan said on Turkish television that Turkey would take whatever steps were necessary if the United States fails to fulfil its pledge to help in the fight against Kurdish rebels, but he appeared reluctant to order an invasion before the elections.