The Nimitz-class aircraft carrier USS Abraham Lincoln transits the Strait of Gibraltar on April 13, 2019.U.S. Navy / Mass Communication Specialist 2nd Class Clint Davis / Reuters

“The United States is not seeking war with the Iranian regime,” National Security Adviser John Bolton said in a Sunday-night statement announcing that U.S. warships were headed to the Middle East. But “any attack on United States interests or those of our allies will be met with unrelenting force.”

In the year since President Donald Trump left the Iran nuclear deal, his administration has steadily ratcheted up economic pressure against the Iranian regime, deploying an unprecedented number of sanctions to throttle its oil exports and punish its support for regional proxies. With Sunday’s announcement, though, Bolton invoked unspecified Iranian threats to the U.S. and its regional allies, while hinting at a more serious step: the threat of violence.

Bolton’s announcement could ultimately represent just that: a threat. But the announcement fit the harsh tone of an administration that has repeatedly demanded behavior change from Iran and condemned its regional activities, support for terrorists, and nuclear-weapons ambitions. It also fit a pattern of bellicose rhetoric from an administration fond of invoking “all options” to scare rivals into backing down. The pattern has shown up in North Korea and Venezuela, where neither policy change nor military strikes has yet resulted. But when it comes to Iran especially, it’s anyone’s guess when exactly the bluster will become reality.

Administration officials have not so far disclosed what exactly prompted the worries about Iran targeting the U.S. or its allies, with Acting Secretary of Defense Patrick Shanahan, for instance, only citing “indications of a credible threat by Iranian regime forces.” Still, the dynamics of the region, and especially how deeply entrenched both Iranian and U.S. forces are there, have left the Iranians with plenty of opportunities to harass America and its allies if they choose.

Iranian forces or their proxies operate close by U.S. and U.S.-backed forces in both Iraq and Syria. Iran routinely threatens to disrupt the world oil trade through the Strait of Hormuz off its coast; its aligned forces in Yemen and the Gaza Strip directly threaten U.S. allies in Saudi Arabia and Israel with rocket attacks.

The carrier strike group (CSG) that Bolton announced was headed to the Middle East had actually departed for a scheduled deployment more than a month ago. “Carrier deployments take some time to plan and aren’t sudden decisions, although their course is more flexible,” Becca Wasser, a policy analyst at the RAND Corporation, wrote in an email. “Bolton’s statement merely leveraged an existing and ongoing deployment to send a message to Iran. It is important to note that he or the White House did not suddenly order the CSG to deploy.”

The chief of naval operations, Admiral John Richardson, confirmed as much to reporters at an event Monday, according to U.S. News & World Report, though he later tweeted that the carrier strike group would go to the Middle East “at the direction” of Bolton and Shanahan. Wasser wrote that U.S. military strategy now calls for more unpredictability to confront rivals like Iran. “The U.S. Navy—and all services—has adopted dynamic force employment to demonstrate flexibility and the ability to respond to contingencies and world events as they unfold,” she wrote.

As harsh rhetoric escalates on both sides, so does the potential for miscalculation. When the Trump administration declared the Islamic Revolutionary Guard Corps a terrorist group, it hoped to render internationally “radioactive” Iran’s dominant security service, which is also a major economic actor. But in announcing the move, Secretary of State Mike Pompeo declined to specify whether the designation, which opens the door to U.S. criminal penalties for anyone doing business with the IRGC, made the group to subject targeting by U.S. forces in the region; a Department of Defense spokesperson told us then that the rules of engagement had not changed. Iranian-backed forces, according to U.S. officials, were responsible for killing more than 600 American service members from 2003 to 2011, but they have uneasily shared the same battle space on the same side against the Islamic State in Iraq and Syria since 2014, and even at times collaborated.

Iran’s response—declaring U.S. forces in the region a terrorist group themselves—was also unclear in its implications, but twice in the weeks that followed a Pentagon spokesperson told us that there was no indication of an imminent threat to U.S. forces in the region due to the terrorism designation. Bolton, however, on Sunday cited “a number of troubling and escalatory indications and warnings” without going into further detail. Asked for comment, DOD referred back to Bolton’s statement. On Monday, moreover, The Wall Street Journal reported that Iran was considering abandoning some elements of the nuclear deal that Trump left but that all the other parties have continued to observe.

If the specific warnings about Iran’s intent remain murky, the potential for Iran to threaten the U.S. and allies in the region is serious. (Axios reported on Monday that the U.S. was responding to intelligence from Israel, though the Israeli embassy declined to comment.)

“The reality is, the U.S. is very much exposed in the region,” Ali Vaez, an expert on Iran at the Crisis Group, told us, adding: “The Iranians have plenty of experience targeting U.S. forces in the region indirectly through the use of their Shia militia allies.”

The U.S. has some 2,000 troops in Syria, where Iran and its proxies have a physical military presence; 5,000 security forces in Iraq, where the Islamic Republic remains an influential player; and 14,000 troops in Afghanistan, where Tehran has made common cause with the Taliban in the fight against ISIS. Iran has the means to escalate tensions in any of these countries.

The U.S. has also demonstrated in the past a willingness to strike back. In 2017, the U.S. struck a convoy of Syrian and Iranian-backed militias as it approached a U.S. base in Syria. Brett McGurk, formerly the U.S. special envoy for the global coalition to defeat ISIS, on Monday told MSNBC that “we have no diplomatic channels with Iran whatsoever,” and said the risks of a clash were increasing given that there’s no real way to get messages privately to the Iranians to avoid it.

Iranian proxies could also fire rockets against U.S. bases in Iraq and Syria. Last September, Iranian-backed militias struck the U.S. consulate in Basra, forcing its evacuation, and the U.S. embassy in Baghdad. And in the Persian Gulf, U.S. officials have in recent years cited unsafe or harassing maneuvers by Iranian drones and boats against U.S. planes and ships—in 2016, the Islamic Revolutionary Guard Corps briefly captured 10 U.S. sailors at sea.

“The U.S. is now signaling that it is prepared to retaliate” by emphasizing that it does not distinguish between the Iranian government and its militia proxies, Michael Knights, an expert on the region at the Washington Institute, a think tank that studies the Middle East, told us.

Finally, and most important, there is the world oil trade, which relies heavily on the Strait of Hormuz. Some 18.5 million barrels per day flow through the narrow waterway between Iran and the Arabian Peninsula. After the U.S. in late April threatened with sanctions anyone importing Iranian oil in an effort to drive the Islamic Republic’s oil exports to zero, Iran warned it could close the strait, a move that would wreak havoc on the global economy.

But there are plenty of reasons Iran wouldn’t target the Strait of Hormuz even if it couldn’t export oil through it. Iranian petrochemical exports pass through the strait, as do its non-oil exports and imports. “They’d be cutting their own throat if they close the strait,” Knights said.

Iran is perhaps better positioned to harass American allies in the region, namely Israel and Saudi Arabia. Tehran supports the Palestinian militant group Hamas, which in recent days launched some 600 rockets toward Israel from its territory in the Gaza Strip. Iran could also encourage the Houthis in Yemen, another of its regional allies, to start targeting Saudi and Emirati oil shipments headed to Europe. (The two countries have taken over Iran’s market share following the imposition of U.S. sanctions.) The Houthis have already launched rockets at Saudi Arabia during their ongoing war against the country’s internationally recognized government, which the Saudis back.

Iran has “plenty of options,” Vaez said. “The problem is, given that there are no off-ramps, and no channels of communication between the two countries, the risks of a confrontation quickly spiraling out of control are quite high.”

Yara Bayoumy contributed reporting.

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