DUBAI—Middle East mediators are scrambling to revive talks with Iran, fearful that hostilities could flare anew as the U.S. moves another aircraft carrier to the region and Israel warns that it has prepared plans for possible new strikes.

President Trump has said the U.S. won’t attack Iran before U.S. midterm elections on Nov. 3. But he has also sounded hawkish notes, threatening Sunday on social media that unless Iran rapidly changes its behavior, the U.S. and Israel “will soon finish the job.”The U.S. military has been preparing a range of options to strike Iran, officials familiar with the planning said. Two aircraft carrier strike groups are currently in the Middle East, with a third on the way from the Pacific. It is unclear if all three will stay in the Middle East.

The U.S. is also bringing in another amphibious assault ship loaded with Marines and has moved some troops off bases in the region and out of harm’s way as Iran and Houthi militants have threatened Gulf allies, the officials said. The Houthis have launched attacks on Saudi Arabia, and the State Department recently ordered nonemergency U.S. government employees and their family members there to leave.

Israeli Prime Minister Benjamin Netanyahu has been pushing publicly to restart strikes on Iran. His military prepared for a multiday bombing campaign earlier this month that would have struck at civilian, nuclear and regime targets, a person briefed on the planning said.

The attack didn’t happen after Trump publicly opposed restarting the war before the coming congressional elections, the person said. The planned Israeli strikes were previously reported by the Financial Times.

White House spokeswoman Anna Kelly said that U.S. wouldn’t be attacking Iran “at any time prior to the midterm elections.” [video] Aboard a U.S. Carrier Preparing for Potential Operations Against Iran Capt. Tim Hawkins, spokesman for U.S. Central Command, which is responsible for the Middle East, said the military regularly moves assets and doesn’t discuss them for operational security reasons. The office of Israel’s prime minister didn’t reply to a request for comment. Regional officials said they are taking the risk of escalation seriously given Trump’s threats and Iran’s unwillingness to bend to U.S. demands.

The U.S. is pressing Iran to enter negotiations over its nuclear program, while Tehran wants to limit talks to reopening the Strait of Hormuz. The diplomatic track has been stuck for months.

Iran has sharply increased strikes against ships in the strait. Oil flows through the narrow waterway have surged, however, as shippers, with the guidance and protection of U.S. forces, manage to make their way through. At the same time, Iran’s Houthi allies in Yemen have launched a wave of missile and drone attacks on energy facilities and airports in Saudi Arabia.

The U.S. has raised the level of economic pressure on Tehran by blockading oil shipments and tightening sanctions, but that has so far failed to bring about a breakthrough.

Pakistan’s army chief, Asim Munir, flew to Tehran on Tuesday followed by a delegation of Qatari diplomats in an effort to break the deadlock.

Mediators have floated offers including the release of some Iranian funds frozen overseas with interest in exchange for nuclear concessions such as allowing international inspectors, some of the mediators said.

Other ideas include transferring Iran’s enriched uranium stocks to Russia, they said. Iranian diplomats initially showed some openness to the idea of allowing international inspectors to return, but they were shut down by Iranian hard-liners, some of the mediators said.

Iranian officials were angered by the message from mediators that they would need to engage in a serious round of negotiations to head off a resumption of U.S. attacks on Iran, they said. Iranian Foreign Minister Abbas Araghchi wrote in an opinion column in the Financial Times that Iran is only willing to negotiate if the U.S. gives up its military options and would respond aggressively across the region if attacked.

“I am duty-bound to warn that any further escalation around the Strait of Hormuz or elsewhere in the region will put civilian lives and the wellbeing of all regional states and the global economy at great risk,” he wrote.

The warning echoed private threats from Iranian officials that any new round of escalation would be costly and would target Gulf energy infrastructure and other economic assets along with U.S. bases, some of the mediators said.

The U.S. has around 20 warships in the region right now.

The incoming carrier strike group and Marine unit are expected to bring the total to more than two dozen if other ships don’t rotate out, significantly expanding the Navy’s ability to conduct round-the-clock operations and give Trump more options for amphibious landings or other missions. Trump has publicly mulled attacking Iran’s Pickaxe Mountain nuclear site, and he has previously ordered strikes on Iranian targets near the strait to hamper Iran’s ability to attack commercial ships.

Netanyahu has been pushing to restart strikes in Iran, a person briefed on his thinking said.

Israel’s military has been busy updating its target list, saying it is worried Iran is making fast progress rebuilding its infrastructure and missile and drone capabilities. Israel presented U.S. Defense Secretary Pete Hegseth with strike targets based on new intelligence during a meeting Monday at an Israeli air base, the person said.

The country’s military has been on high alert for several weeks.

A large number of U.S. military personnel remain in Israel and refueling tankers are stationed at Israel’s main airport as well as air force bases in the south. The U.S. and Israel carried out more than 20,000 strikes on Iran during the most active phase of the war.

Iran responded by raining missiles and drones across the Gulf, hitting crucial energy infrastructure as well as airports, U.S. bases and American embassies and consulates. Defending against that barrage has eaten into stockpiles of missile interceptors needed to fend off future attacks. Trump has ramped up threats of attacks on Iran previously only to back down and try to cut a deal—most recently in late July.

“We want to make sure that Iran never gets a nuclear weapon,” Hegseth said on Tuesday after his trip to the Middle East.

“If they’re not willing to give it up, and the president asks us to go even further, we’re prepared.”