Five U.S. senators who visited North Korea Friday and today said that country's civilian communist leaders warned them of a potential "rift" with their powerful military leaders that could threaten proposed peace talks for the Korean Peninsula. But the senators cautioned that the warning could be simply a negotiating ploy.

The Americans, on a fact-finding mission to the Stalinist nation, said they were told military leaders were adamant that North Korea must receive massive amounts of food aid from the United States and South Korea before the nation agrees to participate in proposed peace talks involving the two Koreas, the United States and China.

"They were quite clear in saying that if they were unable to get food supplies, they were not sure how the military would respond to them going to the four-party talks," said Sen. Pete V. Domenici (R-N.M.), as the senators met with reporters at this U.S. air base outside Tokyo on their return trip to the United States. But Sen. Daniel Inouye (D-Hawaii) stressed that the North Koreans' repeated references to the problem were merely "part of their negotiating posture." He added that it was his impression that the North Koreans were open to compromise and they were using the fear of military restlessness as a negotiating ploy.

The bipartisan group led by Sen. Ted Stevens (R-Alaska), chairman of the Senate Appropriations Committee, was the highest-ranking congressional delegation to visit reclusive North Korea in years.

During their visit, the senators said, they found the capital, Pyongyang, engaged in a massive self-defense exercise in which all cars were covered with camouflage netting and thousands of people took refuge in underground tunnels and shelters. They said they were told the "total mobilization" drill was to prepare for what North Korean leaders believe is a potential invasion by the United States, South Korea or others.

"They live in a very different reality than we do," Domenici said. "There's nobody ready to attack them, but this is just part of the way they live, as far as I could tell."

Observers of North Korea speculate endlessly about whether leader Kim Jong Il has full control over the massive military machine in his country, which is believed to be the most immediate threat to Kim's government and to peace on the peninsula.

Previous visitors to North Korea have said they sensed that there were differences between the civilian leaders and the military, but the senators' statements today were the most blunt assessment in some time of such a division. Neither the nation's leader Kim Jong Il nor military leaders met with the senators.

Although congressional Republicans have been highly critical of President Clinton's policies toward North Korea, Stevens today said he told the North Koreans that U.S. policymakers from both parties agree that the four-nation talks are vital to peace on the Korean Peninsula.

Stevens said the United States would not agree to any conditions for the talks. "We sought to leave no doubt that the four-party talks must proceed without preconditions," he said.

Stevens said the group would urge the United States to continue giving humanitarian aid to North Korea but not to comply with North Korea's insistence that such aid be a "precondition."

North Korea is suffering severe food shortages that international aid groups say border on famine. Stevens said the North Koreans want at least 1.5 million tons of food aid, which they estimate to be their minimum food shortfall this year.

"We are going to have a difficult time in our Congress obtaining support for funding for the food if it's looked at as a precondition," Stevens said.

While the senators saw no direct evidence of impending famine, they did see signs of food shortages, even in relatively prosperous Pyongyang. Sen. Pat Roberts (R-Kan.), said rice and vegetables were available to the residents of Pyongyang, but "there is no livestock production. There was not a chicken, there was not a pig, there was not a duck, there was not a goose."

"We weren't in a heated building the whole time," Stevens said.

U.S. officials worry that widespread hunger in North Korea could lead to chaos in an unpredictable nation with one of the world's largest military forces.

Roberts said the group visited a 1,100-acre collective farm just outside the capital that had virtually no supplies or production. He said they were told the farm had 1,400 workers, but the senators saw only four or five. He said the machinery was outdated and there were serious shortages of fertilizer, chemicals and all basic farm supplies.

"They need everything," Roberts said. "It's pretty grim."

The U.S. officials visited a kindergarten at the farm where children studied without lights or heat. "There was no evidence of malnutrition, not to my way of thinking anyway," Roberts said. "But I think throughout the country there are serious food shortages."

Stevens said the delegation was treated to a big dinner Friday night at a hall in Pyongyang: "It's a little hard to eat a dinner like that after listening to tales of the food they need."

Stevens said the North Koreans said they feel "let down" that the United States has not offered more concessions based on a 1994 deal between the United States and North Korea. Under the deal, North Korea agreed to suspend nuclear arms development in exchange for two nuclear reactors and shipments of fuel oil.

The North Koreans have maintained that the United States also agreed to ease trade sanctions and improve bilateral ties if North Korea honored the nuclear deal. U.S. officials have said the North Koreans are asking for too much too fast.

Today, Stevens said the North Koreans feel "backed into a corner" over what they see as Washington's failure to provide more assistance under the 1994 deal. He said the North Koreans believe the U.S. position amounts to "hostile acts" that are "provoking them."

The delegation, which also included Sen. Thad Cochran (R-Miss.), met with South Korean President Kim Young Sam in Seoul Friday. Stevens said the senators told North Korean officials that the United States and South Korea are in "complete unanimity" over how to approach North Korea.