A Biden administration proposal to deploy Marines on board foreign commercial ships in the Persian Gulf to protect naval traffic against Iranian hostilities is drawing skepticism from some military analysts who say the plan is as likely to cause conflict as prevent it.

“This is an exceptionally complex issue,” former Marine Lt. Gen. Dave Beydler told reporters and analysts Tuesday. “The Iranians are very good at making this difficult, if not deadly, in the Region.”

Beydler, who previously commanded all Marines in the region, spoke at an event organized by the Jewish Institute for National Security of America at a time the White House is reportedly considering following through on preparations to embark the armed troops aboard ships as they transit the Strait of Hormuz.

Reports emerged earlier this month that the Pentagon had deployed a specially trained unit of roughly 100 Marine Corps and Navy personnel to the region to finalize training and preparations for the new, and in some ways, unprecedented mission. The Marines, part of the 26th Marine Expeditionary Unit, joined the three-ship Bataan Amphibious Ready Group and were staging in Bahrain, USNI News reports. From there, they were preparing to break into teams of 15-19 to thwart attempts by the naval forces of Iran’s Islamic Revolutionary Guards Corps to harass or even attempt to seize merchant vessels.

It remains unclear how many ships the Marines would board to support and which countries would request the additional defenses.

The Pentagon confirmed the deployment to the region earlier this month but would not comment on specific plans for the troops.

“I don’t have any announcements to make regarding any force posture changes,” Air Force Brig. Gen. Pat Ryder told reporters on Aug. 3, citing the units as well as the deployment of several kinds of fighter jets and attack aircraft to support them. He declined to offer any other specifics, saying, “As it pertains to that particular reporting, I don’t have anything to provide.”

Beydler on Wednesday said that Marines routinely train for similar missions but noted the rarity of preparing for potential confrontations with Iranian forces over civilian vessels. And merely deploying them to the region amid reports of their intended use could prove enough to contain Iran’s aggression.

“Merely saying it will lend itself to deterrence, I believe. It’s not unlike the air marshal program, if you will – if you don’t know where the Marines are, you may be reluctant to do anything in the region where you may encounter Marines,” he said. “When you say, ‘Marines,’ there is a threat that comes with that. When we say we’re going to embark Marines, we mean business. And I think people take that to heart around the region and around the globe.”

Iran, for the moment, however, appears undeterred. Earlier this month its chief diplomat said that the region does not need “foreigners” to provide security. On Aug. 3 the Revolutionary Guard launched a surprise drill on a series of disputed islands in the Gulf involving small fast boats – its preferred method for harassing ships in the region – as well as paratroopers and missile units.

The burgeoning threat to the region, through which 20% of the world’s crude oil exports pass, also comes as Iran has again begun to enrich uranium at a level closer than ever to what it needs to produce nuclear weapons, following President Donald Trump’s unilateral decision to withdraw from the international deal governing its nuclear program.

The current dangers pose even graver problems as communications between the U.S. and Iran – in part because of Trump’s decision to withdraw from the deal – have sunk to all-time lows with no clear path for how the two countries would deescalate a potential armed conflict.

“We do interact with the Iranians at sea, every day,” retired Vice Adm. Mark Fox, the former deputy commander for all forces in the region, said at the same event. He was referring to the global standard for communication between all kinds of vessels, from small merchant boats to navy warships. “They’re not professional and they’re not necessarily responsive.”

He noted that, as a ship commander and later deputy U.S. Central Command chief, he did not have any method for directly contacting his Iranian counterparts to deconflict a potential problem.

“If somebody doesn’t want to talk to you, then it makes it very difficult,” he said, adding that the U.S. military typically coordinates with Iran through common surrogates, such as partner governments in the region. But he warned of the high potential for escalation, particularly if the U.S. is considering introducing new armed forces to confront Iran.

“When you can’t communicate, you create such potential for miscalculation,” Fox said.

Beydler referenced the “mile-long list” of considerations that U.S. military commanders will have to work through in advance of following through on the deployment, to include the clear rules of engagement for the Marines, when they can use deadly force and who authorizes direct engagement with potential enemy troops.

“Escalation is easy,” Beydler said. “Deescalation is really, really hard.”

Others with experience in the region have similarly noted the challenges, and how comparable operations in the past have had dangerous consequences.

“There are plenty of risks in taking this aggressive but necessary stance,” retired Navy Adm. James Stavridis wrote in a recent op-ed for Bloomberg. “A decade ago, when I was the military commander of the North Atlantic Treaty Organization, we tried similar methods using both marines and civilian security forces in counter-piracy operations. Unfortunately, we had several instances of significant ‘collateral damage’ to fishing vessels and small civilian craft in the area. Two Italian marines mistakenly shot at Indian fishing vessel in 2012, killing two fisherman, and were prosecuted for years until India’s supreme court dropped the charges.”

However, Stavridis still advocates for the Biden administration to follow through in challenging Iran’s acts of aggression.

“The risk of quick escalation in the Gulf is ever present — just as in South China Sea, where American and Chinese ships have had regular face-offs,” he wrote. “Yet the alternative — continuing to sanction the Iranians, scold them diplomatically and hope their behavior improves — won’t work.”

“Allowing Iran to control the Gulf and that vital chokepoint is unacceptable,” he added. “Putting U.S. Marines ‘on deck’ of vulnerable civilian merchant ships makes sense, and shows Iran we are deadly serious about freedom of the seas.”