ANKARA, Turkey (AP) --- Hundreds of Kurds had to flee their homes in the mountain village of Razqa, Iraq, when artillery shells came whistling down from Iran early this month, blowing apart their homes and livestock.
In Turkey, meanwhile, armored personnel carriers and tanks rumble along its remote border with Iraq's Kurdish zone. Turkey has sent tens of thousands of fresh soldiers in the last few weeks to beef up an already formidable force there.
The Kurdish provinces of northern Iraq are the country's most stable and prosperous area. But to neighboring Iran and Turkey, both with large Kurdish minorities, they are something else: an inspiration and a support base for the Kurdish militants in their own countries.
So Iran and Turkey are sending troops, tanks and artillery to the frontier to seal off the borders and send a message: If the U.S.-backed Iraqi government doesn't clamp down on Kurdish guerrillas who use Iraq as a base, they could do it themselves.
That has left the United States in a quandary. If U.S. forces take action, they risk alienating Iraqi Kurds, the most pro-American group in the region. And if they don't, they risk increased tensions -- and possibly worse -- with two powerful rivals.
Just listen to Turkish Foreign Minister Abdullah Gul.
"We would not hesitate to take every kind of measures when our security is at stake," Gul said when asked whether Turkish troops might cross into Iraq. "The United States best understands Turkey's position. Everybody knows what they can do when they feel their security is threatened."
Iran's artillery barrages could be warning shots, a crackdown on Kurdish guerrillas now as a factor in the wrangling with the United States over Tehran's nuclear program.
Kurds, who make up 14 percent of Iran's population, have long complained of discrimination in Iran. Iraq's Kurds backed the U.S. invasion of their country. Would the Kurds of Iran take the American side if tensions escalated there?
"The Iranians are clearly very concerned over the mobilization of their own Kurdish minority," said Toby Dodge, an Iraq expert at Queen Mary College, University of London.
And Tehran may also be flexing its muscles to remind the United States that it shares a long border with Iraq, and could cause serious problems there for the United States.
The Iranians' policy is to warn that "we have the potential to run you out of Iraq if you don't give us some slack over the nuclear issue," Dodge said.
The traditional Kurdish region spans Iran, Iraq, Turkey and Syria and the guerrillas are based in a mountain range of northern Iraq that stretches into Turkey and Iran. They seem determined to keep up their decades-long struggle.
Kurdish guerrillas of the Party of Free Life of Kurdistan, or PEJAK, have called on Kurds in western Iran to begin a campaign of civil disobedience. In clashes with Iranian security forces last year, dozens of PEJAK fighters and about a dozen Iranian soldiers were killed, according to official Iranian reports.
This year, more than a dozen members of Turkish security forces in southern Turkey have been killed fighting Kurdish guerrillas of the Kurdistan Workers Party, or PKK, which is closely allied with PEJAK.
After Iran shelled a village used by Kurdish guerrillas, the PKK warned that it was "capable of responding to these attacks with more strength then ever."
The attacks, which heat up in the spring when snow-covered mountain passes clear, have led to the military buildups along the borders. Turkey and Iran have both rushed tens of thousands of troops to the area.
Iran has twice shelled Iraqi Kurdish villages believed to be harboring PKK militants.
As the Iranians bombarded Razqa on May 1, hundreds of people fled. The shelling killed some farm animals but there were no reports of human casualties. Several homes could be seen severely damaged and holes from shells cratered the streets.
Olla Hamad, a villager, said most of the guerrillas are hiding in the mountains.
"PKK militants do not care about the bombings," he said, pointing toward the heights near the village. "They hide in safe rocky places in the mountains."
A Western diplomat said Turkish officials have hinted to the United States that they are considering a large-scale military operation across the border.
In a visit to Turkey in late April, Secretary of State Condoleezza Rice warned against any major strike.
"We want anything we do to contribute to stability in Iraq and not to threaten that stability or to make a difficult situation worse," Rice said at a news conference with Gul.
The Western diplomat said Iranian troops on the border are not front-line combat troops and Washington does not believe there will be any Iranian cross-border operations. The diplomat agreed to discuss the situation only if granted anonymity because of the subject's sensitivity.
Some analysts say that besides sealing off their borders to the guerrillas, both Iran and Turkey may be trying to intimidate Iraqi Kurds. The Iranians and Turks fear Kurdish success in creating an autonomous region in northern Iraq, and the prosperity of their enclave, could encourage their own Kurdish minorities.
"The Iranians and the Turks do not want a free Kurdistan there," said Nazmi Gur, vice president of Turkey's pro-Kurdish Democratic Society Party. "They are saying to the Kurds 'We are here.'"
By Louis Meixler
Associated Press writer Yahya Barzanji in northern Iraq contributed to this report.