The “Clock is Ticking” for Iran, President Donald Trump has warned, as deadlocked diplomacy and new drone attacks against U.S. allies in the Gulf fueled fears of a renewed outbreak of war.

Trump said Sunday on Truth Social that Iran had “better get moving, FAST, or there won’t be anything left of them,” reviving his threats to annihilate the country with efforts stalling to end to the war the U.S. and Israel began nearly three months ago.

Talks over a deal that would end the conflict, address Iran’s nuclear program and restore traffic through the Strait of Hormuz appear to have made little progress in recent weeks.

Iranian Foreign Ministry spokesman Esmail Baghaei appeared to respond to the threat Monday, saying that Tehran was not “intimidated” but emphasizing that the “process of talks and negotiations” remained “ongoing.”

Tehran had now responded to a new U.S. proposal, Baghaei said. “Our concerns were conveyed to the American side,” he told a news briefing.

Trump’s warning came as the president spoke with Israeli Prime Minister Benjamin Netanyahu on Sunday, according to Israeli media. The White House did not confirm the call.

It also came as the United Arab Emirates said a drone strike caused a fire at a nuclear power plant, while Saudi Arabia reported intercepting three drones from Iraqi airspace.

The U.A.E. did not identify an assailant in what it called an “unprovoked terrorist attack” on the perimeter of its Barakah nuclear plant.

Authorities said Sunday that the fire did not affect the plant’s safety and that all units were operating as normal.

The emirate has frequently accused Iran of carrying out attacks, including during the shaky ceasefire, and this latest incident came as both Tehran and Washington signaled they were prepared for a return to fighting should no resolution be reached in the coming days.

The attack was swiftly condemned by countries including mediator Pakistan.

Trump told Axios in a phone call that if the Iranian regime did not come forward with a better off for a deal to suspend the country’s nuclear program, the Islamic Republic was “going to get hit much harder.”

The president declined to give a specific deadline for the negotiations, but said he wanted a better proposal than an offer given several days ago, according to Axios.

Sen. Lindsey Graham, R-S.C., on Sunday called for a ramping up of U.S. military action in Iran.

The longer the Strait of Hormuz remains closed as the U.S. tries to “pursue a deal that never happens, the stronger Iran gets,” the South Carolina senator told NBC News’ “Meet the Press.”

The effective Iranian closure of the crucial waterway and U.S. naval blockade have throttled global supplies of energy and fertilizer.

Oil prices rose on Monday, with the international benchmark Brent crude climbing above $110 per barrel, while global markets tumbled. Fatih Birol, head of the International Energy Agency, said at a G7 meeting in Paris that commercial oil inventories were depleting rapidly and only had a few weeks left.

Baghaei, Iran’s foreign ministry spokesman, said Monday that Tehran had no enmity with any countries in the region, including the U.A.E.

He said that Tehran would be “monitoring all movements” and was “prepared for any possibility” should Trump move forward with his threat to restart the war with the Islamic Republic. “If they make even the slightest mistake, we know very well how to respond,” he said.

He emphasized that Iran was not willing to compromise on its right to nuclear enrichment, which he said was enshrined in the Treaty on the Non-Proliferation of Nuclear Weapons, the international treaty aimed at preventing the spread of nuclear weapons.