The U.S. has in recent days sent U-2 spy planes to the border area to try to collect better information on the militants and regional Iraqi authorities have sent some of their troops there, one official said.

Turkey has complained for months about what it has said is a lack of U.S. support against the rebels from the Kurdistan Workers' Party, known by its Kurdish acronym PKK. And Ankara has threatened a full-scale ground attack into northern Iraq if the U.S. and Iraqi officials don't do something about the rebels.

"We have given them more and more intelligence as a result of the recent concerns," said Defense Department Press Secretary Geoff Morrell.

"There has been an increased level of intelligence sharing as a result of this," he told Pentagon reporters Wednesday.

He did not say specifically when the increase started or how the intelligence was being gathered.

But the military in the last week or so has sent manned U-2 spy planes to the border region used by rebels, said a second defense official, speaking on condition of anonymity because he was not authorized to speak about it on the record.

The official also said that the U.S. military saw a battalion of several hundred Peshmerga - the militia of the Kurdish Iraqi regional authorities - moving toward the border over the weekend. That could represent a notable change from last week when the top U.S. military commander in the area said he was not aware of any Kurdish attempts to rein in the PKK.

Defense Secretary Robert Gates suggested last week that airstrikes or major ground assaults by U.S., Turkish, or other forces wouldn't help much because not enough is known about where the rebels are at a given time.

Asked during a NATO meeting in Europe about the prospects of U.S. military strikes, Gates said: "Without good intelligence, just sending large numbers of troops across the border or dropping bombs doesn't seem to make much sense to me."

The U.S. and Iraqi governments have urged Turkey not to send troops across the border to pursue the separatist Kurds, calling for a diplomatic solution. They fear a large military operation, opening a new front in the Iraq war, would unsettle what is now the most stable part of the country.

A Turkish incursion would also put the United States in an awkward position with key allies: NATO-member Turkey, the Baghdad government and the self-governing Iraqi Kurds in the north.

Turkey's Prime Minister Recep Tayyip Erdogan said Tuesday that it was "unavoidable that Turkey will have to go through a more intensive military process" to counter the rebels. Turkish forces have been shelling rebel positions near the border.

Erdogan also suggested he was not seeking an immediate cross-border offensive against the rebels. He flies to Washington for talks with President Bush next week.

"We expect the Iraqis to step up and make sure that they are doing everything they can to eradicate the PKK," White House press secretary Dana Perino said Wednesday.

"Turkey has a right to defend its people, it has a right to look for its soldiers, and we are asking Turkey, as well, to exercise restraint and to limit its exercises to the PKK. And so far that's continuing to work, but it takes a lot of dialogue and discussions," she said.

Maj. Gen. Benjamin Mixon, the top U.S. commander in northern Iraq, said last week that he is planning to do "absolutely nothing" to counter PKK activity - the most blunt assertion to date by an American official that U.S. forces should not be involved in the fight.

Mixon said he has sent no additional troops to the area and has not been ordered to take any action against the rebels.

Top Defense Department and State Department officials have said that Iraq's Kurdish regional government should cut rebel supplies and disrupt rebel movement over the border, adding that Washington is increasingly frustrated by Kurdish inaction.

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