The Iran ceasefire is on the verge of collapse, President Donald Trump said Monday, as Tehran’s latest proposal failed to satisfy U.S. demands and the two sides remained dug in on irreconcilable positions — from control of the Strait of Hormuz to the future of Iran’s nuclear program.

“I would call it the weakest right now after reading that piece of garbage they sent us,” Trump told reporters at the White House. “I didn’t even finish reading it.” He described the truce as on “life support.”

Two regional officials, speaking on condition of anonymity to discuss sensitive diplomacy, told the Associated Press that Iran had offered to dilute a portion of its stockpile of highly enriched uranium and to transport the remainder to a third country. Russia has previously indicated a willingness to accept it. The concession, however, was not enough to keep negotiations on track.

Standing beside the collapsing diplomacy, Trump proposed a temporary suspension of the 18.4-cent-per-gallon federal gasoline tax, telling reporters that oil and fuel prices would drop “like a rock” as soon as the fighting stopped. Congress would need to approve any suspension. The tax pulls in more than $23 billion a year for the Highway Trust Fund. The average retail price of gasoline has surged past $4.50 a gallon as the Strait of Hormuz — the narrow chokepoint through which roughly a fifth of global oil trade normally moves — remains closed under Iranian control.

Iran’s Fars news agency posted video Monday that it said showed vessels in the northern part of the strait, which Tehran has kept effectively shut since the outbreak of the war. The closure, combined with the U.S. naval blockade of Iranian ports, has choked global energy markets and sent fuel costs climbing worldwide.

The two sides remain divided over the scope and sequencing of any deal. Trump has insisted on a major rollback of Iran’s nuclear activities, claiming Monday that Iran had previously agreed to let U.S. specialists help extract its highly enriched uranium but then backed away. “They changed their mind because they didn’t put it in the paper,” he said. Iran has never publicly agreed to give up its uranium, maintaining that its enrichment program is entirely peaceful and protected by international law.

Iran’s proposal, aired by state television, would grant it formal sovereignty over the Strait of Hormuz — an arrangement legal experts say would violate freedom-of-navigation rights under international law. Tehran is also demanding war reparations from Washington, the lifting of international sanctions, the release of frozen Iranian assets, and an end to the conflict between Israel and Hezbollah in Lebanon. Israeli forces and the Iran-backed militant group have continued to trade fire in southern Lebanon despite a nominal ceasefire that took hold last month.

“We did not demand any concessions — the only thing we demanded was Iran’s legitimate rights,” Iranian Foreign Ministry spokesman Esmail Baghaei told reporters Monday. “The American side still insists on its one-sided views and unreasonable demands.”

Israeli Prime Minister Benjamin Netanyahu, who launched the war alongside Trump on Feb. 28, sharpened his own position in an interview that aired Sunday on CBS’s “60 Minutes.” If negotiations cannot accomplish the removal of all highly enriched uranium from Iran, he said, “we can reengage them militarily,” and emphasized that the U.S. and Israel are in agreement on that point.

Trump is expected to press Chinese President Xi Jinping to lean on Tehran when the two leaders meet this week. Beijing is the largest buyer of Iran’s sanctioned crude, a relationship that gives it significant economic leverage over the Iranian regime.

Meanwhile, Pakistan is continuing its quiet efforts to broker a compromise. Two regional diplomats familiar with the talks said Islamabad is trying to arrange a memorandum of understanding that would end the war and open the door to broader negotiations on outstanding disputes. One of the diplomats said Pakistan had hoped to finalize the memorandum last week, but the effort did not materialize and mediators are still working through various proposals. The diplomat added that Islamabad is receiving support from other countries in the region.

As diplomatic channels strained, Iran pressed ahead with domestic repression. State-run IRNA news agency reported that Erfan Shakourzadeh had been executed after being convicted of spying for the CIA and Israel’s Mossad — part of a surge in hangings that Iran’s judiciary chief has described as retaliation against enemies at home and abroad. Activist groups have long charged that such trials are conducted behind closed doors and deny defendants a meaningful defense. The execution is the latest in a wave that has followed nationwide protests that swept Iran starting in January.