The traffic comes all day long, taxis and trucks and private sedans darting across the plain of government-controlled Iraq toward the mountains where ethnic Kurds maintain their autonomous zone. It is a routine passage from confinement to relative freedom, and last week the Iraqi government made a glancing effort to make it more difficult, imposing a limit of 21/2 gallons on what a taxi can purchase at the last chance for gas in government territory.

But the travelers continue to cross, with their luggage and jerrycans and their intriguing details about a country on the cusp of war.

Secrets have always transited this place with the same ease as battered white and orange taxis. It's a porous line that separates the zones, and people from both sides easily negotiate checkpoints that, on the Kurdish side, often amount to a brake and a wave.

The information flows thickest from Kirkuk, which after Baghdad would be perhaps the most crucial prize of a military campaign against Iraq. If Turkey permits U.S. troops to use its territory to open a northern front in an Iraqi war, analysts say, Kirkuk would figure prominently in the Americans' plans.

Barely 20 miles from the checkpoints, Kirkuk lies on an open plain defended by a trench line facing north and tens of thousands of soldiers and citizens who have far more guns than will to use them, according to Kurdish officials and Kirkuk residents visiting the Kurdish region.

"The regular army doesn't find enough to eat, so I don't believe they'll fight," said a young man visiting the Kurdish-controlled city of Sulaymaniyah for the Muslim holidays last week. His account, like those offered by other travelers and by officials here in the Kurdish zone, could not be independently verified.

The youth said he has seen army conscripts in tattered uniforms and damaged shoes, too poor to afford bus fare to their homes in southern Iraq. "The Republican Guard," he said, "is the only force the government will trust." Well-paid and well-provisioned, Republican Guard troops are regarded here as formidable fighters. An unspecified number reportedly are deployed in the heart of Kirkuk, reinforced by thousands stationed at Khalid Camp, a vast military complex southwest of the city.

Kurdish officials concur that Kirkuk's outer defenses are manned by a ragged regular army supplemented by perhaps 100,000 civilians who have been given automatic rifles and a month of training. Many are members of the ruling Baath Party; others reported for duty after being told each family must volunteer one member for the makeshift militia. About 20,000 are Kurds -- called traitors by their ethnic brethren to the north, who refer to Saddam Hussein's Kurdish militia as the "donkey army" and boast of infiltrating its ranks.

"Most of this military I call sacrifice military," said Shalaow Askari, a Kirkuk native, veteran Kurdish fighter and a minister in the self-government Kurds have established under the cover of U.S. and British warplanes enforcing a "no-fly" zone since 1991.

"They won't run. They will surrender," Askari said. "The military the Iraqis are counting on are inside the city."

Kirkuk residents say they have seen evidence that Hussein's regime is on its last legs.

"The intelligence guys are not like in the past, because they know they have just a little time," said a resident visiting Chamchamal, just past the front line. Criticism that once might have guaranteed arrest is now voiced in semi-public spaces such as taxis.

"They speak as they like, openly," said the middle-aged man, who asked to be identified only as a laborer.

Kurdish officials spoke of recent information that Iraqi forces have moved missile batteries into the city and to positions on the eastern outskirts. But the most intense speculation is over the fate of the oil fields northwest of town. They are the oldest and most productive in Iraq, which ranks second only to Saudi Arabia in total crude reserves.

Reports that Iraqi forces have planted explosives around the wells percolate regularly into the Kurdish region but have yet to be confirmed by photos or other direct evidence, officials said. After Iraqi forces blackened the skies above Kuwait by blowing up wells as they retreated during the Persian Gulf War, people anticipate the worst in the event of a U.S. invasion.

"This is going to be a big issue, the environmental terrorism," said Barham Salih, prime minister of the Kurdish administration.

Kirkuk is combustible in other ways as well. Long before the discovery of oil, the area was treasured as a homeland for two ethnic groups: the Kurds and the ethnic Turkomen, who speak Turkish. Both have suffered as, during more than two decades of Hussein's rule, thousands of Arabs were moved to the city, where they are now the majority. Kurds have been banned from registering as owners of property unless they took on Arabic names, "so you have to find someone who's Arabic to register the home for you," said another Kurdish visitor from Kirkuk, seeing family for the holidays.

In the city's Kurdish neighborhoods, armed members of Hussein's Baath Party have dug fresh bunkers, fearing revenge killings. "They have to be afraid of the Kurdish, because we have suffered a lot," said the young man visiting Sulaymaniyah. "They have a lot to fear from us."

Kurdish leaders say they cannot stop Kurds inside Kirkuk or Mosul, the city that borders Iraq's oil fields to the west, from taking up the arms they have hidden. Nor, they say, will they prevent Kurds in the north from rushing south to claim their old houses from the Arabs who have taken them as their own.

"They are free to do so," said Jalal Talabani, chairman of the Patriotic Union of Kurdistan, the party that controls the areas north and west of Kirkuk. "We can't control them."

An Iraqi guard station is seen up a hill from the road in Chamchamal, on the border of the autonomous Kurdish area.A security agent, left, checks the identification of a fellow Kurd on the way back from the oil-rich city of Kirkuk, which is under Baghdad's control.