Residents of rebel-held Syrian neighborhoods under siege say the message from the government is clear: Surrender or starve.

Peace talks in Geneva, the first of the three-year conflict, have thrown a spotlight on the plight of cut-off civilians in the central city of Homs, as participants focus on the issue of humanitarian access before turning to the tougher political questions. However, confidence is ebbing that relief will materialize.

The World Food Program has said it is poised to enter besieged areas with 500 bags of family rations and 500 sacks of wheat. But the aid trucks remain stranded outside Homs, and on Tuesday, the U.S. government laid the blame squarely on the government.

“The only reason this assistance has not been delivered is that the regime has refused to let the convoy through,” said State Department spokesman Edgar Vasquez, rejecting government claims that rebel snipers and armed groups were preventing entry. “The regime’s actions speak volumes to how little they value the lives of innocent civilians.”

Syrian Deputy Foreign Minister Faisal Mekdad, in Geneva, said the government wanted to be sure the aid deliveries would not go to “armed groups” or “terrorists,” Reuters news service reported.

“We want them to go to the women and children. We are still waiting for these assurances,” he said.

Several areas of Damascus, considered strategically important because of their proximity to President Bashar al-Assad’s seat of power, are also under siege.

In Yarmouk, a Palestinian refugee camp just outside the capital that has been under a stranglehold for six months, life-saving supplies have not arrived despite assurances by the Syrian government last week, the U.N. Relief and Works Agency said Tuesday. UNRWA officials said they were “extremely disappointed” and urged all sides to ensure access.

Images of emaciated children have been emerging from rebel-held Homs and some Damascus suburbs for months, and residents say malnutrition deaths are mounting. The opposition says the intent is to shatter the morale of areas under the rebels’ control and erode support for their fighters.

“The regime has one slogan: hunger or kneel to us,” said Abu Haider, an activist in the Al Waer neighborhood of Homs who uses a pseudonym for safety reasons.

Residents there describe foraging for food as the siege intensifies and supplies of preserved goods, such as olives, dwindle. The government had also pledged to let women and children leave the city, but as of Tuesday, there was no sign evacuations were underway.

“It’s just political statements. There have been no changes on the ground,” said Abu Rami, a spokesman for the Syrian Revolution General Commission in Homs.

Evacuations have taken place in Moadamiya, one of the besieged areas outside Damascus and also a target of chemical weapons attack last July. Field doctors had reported cases of death from starvation there.

“We are at the most advanced stage of Assad’s starvation weapon,” said Qusai Zakarya. “You just want things to end, no matter when, no matter how.”

That desperation among Moadamiya’s 8,000 remaining civilians led rebels there to agree to a truce last month in exchange for the entry of food aid. Since then, however, the limited deliveries have been linked to demands from the government such as handing over wanted residents or weapons, Zakarya said.

“It’s blackmail,” he said. “They see that starvation destroys a man’s soul and mind before it destroys his body.”

In Yarmouk, just 18,000 of some 160,000 civilians remain, according to UNRWA officials. Some are too sick or old to leave, others left it too late. Opposition groups say dozens have died from hunger as animal feed and grass are substituted for food.

Since receiving government assurances about access, UNRWA said it has delivered 138 food parcels to Yarmouk. Each can feed a family for 10 days. But no deliveries have gotten through for the past week.

“The aid allowed into Yarmouk so far is shockingly inadequate to meet the dire need of these civilians,” said UNRWA spokesman Chris Gunness.

Concern is also growing that the increased scrutiny in Geneva on humanitarian access could hamper, rather than assist, in the brokering of aid deliveries.

“I don’t know where the political negotiations will lead us, but I’m not optimistic, frankly,” Abu Rami said.

Ahmed Ramadan contributed to this report.