Turkey's new incursion into northern Iraq to strike back at Kurdish guerrillas delivered a diplomatic warning shot to U.S. and Iraqi leaders struggling to hold off a divisive conflict.
The latest raid by Turkish troops raised concern among U.S. military officials from Baghdad to the Pentagon, even as they first denied and then downplayed the border crossing in one of Iraq's most peaceful regions.
Analysts said the move signaled growing impatience by the Turks, who have pressed the U.S. to crack down on the separatist Kurdistan Workers' Party, also known as PKK, which launches raids into southeast Turkey from hideouts in Iraq.
"This is a shot across our bow and, more importantly, the Iraqi Kurds' bow - all of us who hope that this doesn't escalate," said Peter Rodman, who until earlier this year was a top international policy adviser at the Pentagon.
While Turkey is a critical ally in the region, the Iraqi Kurds are "the best friends we have in Iraq," said Rodman, now a foreign studies fellow at the Brookings Institution. "So we're in the middle."
On Wednesday hundreds of Turkish soldiers crossed into northern Iraq in pursuit of PKK rebels, in what may have been retaliation for the PKK's assault Monday on a Turkish outpost, where seven soldiers were killed.
U.S. military officials said they could not confirm any large Turkish strike Wednesday, but they quickly noted that the Turks have routinely conducted counterinsurgency raids into Iraq across the mountainous, remote border.
"They continue to fight Kurdish terrorists that have targeted a number of their citizens in their country," Brig. Gen. Perry Wiggins, deputy director of operations for the Joint Chiefs of Staff, told Pentagon reporters. "They are conducting aggressive operations in southeast Turkey - counterinsurgency operations - and they continue to do so."
The Turks accuse Iraqi Kurds of supporting the separatist PKK rebels, who are fighting for independence in Turkey's heavily Kurdish southeast. The Iraqi Kurds once fought alongside the Turkish soldiers against the PKK in Iraq. But since the fall of Baghdad, the Turks have worried that the Iraq war could lead to the country's disintegration and the creation of a Kurdish state in the north.
There are suggestions that the U.S. military may be simply turning a blind eye toward a conflict it does not want to plunge into, in an effort not to alienate its few remaining friends in the region. But diplomatic efforts to calm the situation have stumbled, and the Turkish military has ratcheted up its warnings that a larger-scale incursion may be coming.
"People are basically looking at this as a matter of Turkey defending its sovereignty," said Soner Cagaptay, director of Turkish Research program at the Washington Institute for Near East Policy. He said that as long as there is not a large number of Turkish troops in Iraq on a more permanent basis, the U.S. is likely to continue to have a muted response.
As Turkey prepares for a national election, there also is growing pressure within the country to strike back at the PKK as well as the Iraqi Kurds who may be quietly allowing the rebels to operate.
"Turkey is about to reach its boiling point.," said Cagaptay. "The arguments of rationality will be trumped by popular anger over the PKK."
The increased activity comes after Defense Secretary Robert Gates and Iraqi Prime Minister Nouri al-Maliki on Saturday cautioned Turkey not to send troops into northern Iraq.
But Turkey's political and military leaders have been debating whether to try to root out the rebel bases, and perhaps set up a buffer zone across the frontier as the Turkish army has done in the past. And, the Turk's military chief said last week that his army was ready and only awaiting orders for a cross-border offensive.
Any U.S. intervention would be difficult both diplomatically and militarily.
"The nightmare scenario is at a time when Kurdish soldiers are fighting along side U.S. soldiers in Iraq," said Bulent Aliriza, a Turkish scholar at the Washington-based Center for Strategic and International Studies.
If the U.S. takes military action against the Kurds or simply allows the Turks to come in from the north, "it's really caught in an impossible position, and frankly it's going to get worse," he said. "That's the reason the U.S. has not been able to move."
But Rodman said the U.S. military should not be the answer to the problem.
"This is not something we could easily take on," he said. "We don't have a mission there. This would be a big, new, complicated mission. Chasing these people in the mountains is a daunting task."