Iran’s message is stark: If the U.S. and Israel restart their air campaign, Tehran will respond with strikes not only on American bases and warships but on airports, pipelines and other civilian targets in the neighboring countries of the Persian Gulf.

The warnings, issued publicly and in private diplomatic communications, are clearly aimed at deterring any attack with tough talk. But they also signal a real threat. Iran retains significant missile and drone stocks and the ability to use them.

Analysts estimate Iran has hundreds to thousands of ballistic missiles, and U.S. and regional officials believe it has resumed production of ballistic missiles in limited numbers using stockpiled components and working in underground facilities.

In the opening phase of the war, Iran inflicted significant damage on U.S. air bases, embassies and the headquarters of the U.S. 5th Fleet in Bahrain. It also hit energy and industrial facilities in the United Arab Emirates, a major gas plant in Qatar and airports in Dubai, Kuwait and Bahrain.

Tehran says it would seek to cause more pain in any new round, at a time when stockpiles of the air-defense interceptors the U.S. and Arab militaries need to absorb any attack have been running down. Israel’s interceptor supplies have also been under pressure.

Raising the ante in any new fight would expose Iran’s infrastructure to attack when its economy is teetering. Its missile arsenal and launchers were battered by U.S. and Israeli attacks early in the war—the Pentagon said in September the U.S. had destroyed up to 90% of Iran’s drone, ballistic missile and naval industrial base—limiting its ability to sustain a long exchange. Still, analysts believe it would run the risk.

“The consensus in Tehran now believes that deterrence requires imposing immediate, sustained and substantial costs on its adversaries,” said Sina Toossi, an Iran expert at the Center for International Policy, a Washington think tank.

Yemen’s Houthi militants, working with training and technology from Iran, have hit Saudi Arabian refineries and shut down air traffic to the capital with a series of long range missile and drone attacks that Tehran could replicate. Drones fired from Iraq knocked the kingdom’s East-West pipeline out for days, threatening oil supplies.

With negotiations to wind down the war stalled for months, Trump has warned the U.S. could attack Iran after the U.S. midterm elections on Nov. 3. And the U.S. and Israeli militaries have been preparing a range of options for strikes.

The U.S. has a third aircraft carrier strike group and an additional Marine expeditionary unit on the way to the Middle East, and Gulf states believe the combination of threats and stalled diplomacy make an escalation in fighting likely.

[video] Aboard a U.S. Carrier Preparing for Potential Operations Against Iran In addition to bringing in more forces and munitions, the U.S. is working to get more of its servicemembers and diplomatic staff out of harm’s way.

The military has moved some troops off bases in the region, as Iran and its Houthi militant allies have threatened the Gulf.

The State Department recently directed nonemergency U.S. government employees and their family members to leave Saudi Arabia amid the threat from the Houthis. It also has led to a reshuffling of families from some other Middle East embassies, a U.S. official said, reducing its footprint as risks grow.

Iranian officials have told mediators the country will expand attacks across Gulf nations, including their economic assets, in the event of new U.S. strikes, people familiar with the threats said.

They also said they would more aggressively target U.S. personnel, including by trying to sink U.S. warships in the Middle East and kill their crews, the people said.

Brigadier General Yadollah Javani, the Islamic Revolutionary Guard Corps’ deputy commander for political affairs, said Wednesday that Iran could sever internet cables that run beneath the Strait of Hormuz.

Iranian Foreign Minister Abbas Araghchi wrote in an opinion piece in the Financial Times that new attacks “will put civilian lives and the wellbeing of all regional states and the global economy at great risk.”Iran runs the risk of overreaching if it tries to make good on all its threats, said Saeid Golkar, an expert on the Revolutionary Guard at the University of Tennessee at Chattanooga. The country needs to carefully manage its shrinking stockpile of missiles, he said.

Farzin Nadimi, an Iran-focused senior fellow with the Washington Institute, a U.S. think tank, said Tehran will also have to factor in the likelihood of U.S. and Israeli retaliation.

“They certainly have the capability to inflict major damage to the region’s energy and internet infrastructure,” he said. “But if Iranians do that they’ll most likely lose their own in reciprocal attacks.”Experts say Iran can count on asymmetrical strategies that inflict heavy damage at low cost. Since the beginning of the month, Iran has stepped up its strikes on vessels in the Persian Gulf area. Two ships sank last week after being hit.

Concerns the Revolutionary Guard had planned a drone attack on U.S. bombers at a base in Britain led the Air Force to move them back to the U.S.

Some of Iran’s more recent missile strikes have shown greater capabilities than previously, including a July strike on the Muwaffaq Salti Air Base in Jordan that killed three U.S. servicemembers. Iranian missiles came close to American warships during attacks in September.

U.S. officials are concerned Iran may be getting help from Chinese entities with satellite imagery and help tracking American warships. China has rejected what it calls malicious attempts to smear the country.

On Sunday, Iran’s parliament appointed Mehrdad Akhlaghi, one of the fathers of the country’s ballistic program, as defense minister. After taking the position, which had been vacant since the killing of his predecessor in February, Akhlaghi said Thursday he would be focusing on new technologies.

“We can dismiss their threats as bluffs, but then they have surprised throughout this war,” said Vali Nasr, a former senior State Department adviser. “So if anything we should be cautious in discounting the threats. I am not sure their capabilities are diminished.”