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Other scholars say the IRGCN also has a decentralized decision-making structure and a culture that prizes aggressive independent action.

In 2007, two IRGCN small boats seized 15 British Royal Marines who the Iranians said were in their waters “apparently without orders from headquarters,” said David B. Crist, a U.S. Marine Corps historian.

Mr. Crist said the commander responsible, Capt. Abol Qasem Amangah, was rewarded with a medal after the Marines were held in Tehran for two weeks and then released.

Cmdr. Himes argued that the role of the IRGCN in a globally vital shipping zone like the Gulf makes it more likely that a small incident could escalate into a strategic confrontation.

“This could be calculated, or it could be the result of less professional or more zealous decision-making at lower command levels,” he wrote.

Mr. Cordesman said that if he were Iran, he would concentrate on ratcheting up the pressure with low-level provocations “anywhere in the Gulf or outside it” that “don’t justify a massive use of coalition military force” in retaliation.

For Tehran, he said, this is “a long-term game of pressure, intimidation and leverage” in the region.

The IRGCN has honed its tactics since the “tanker wars” of the 1980s, when it mined Gulf shipping lanes and sparred intermittently — and disastrously — with U.S. forces, Cmdr. Himes noted.

“What’s different and more dangerous now … is the ambient temperature is much, much higher,” said Barbara Slavin, a senior fellow at the Atlantic Council. “It’s a colossal game of chicken.”

Iran has parliamentary elections coming up in March, she added, which “might create a temptation on the part of some elements of the regime” to provoke a confrontation with United States.

She said recent reports she heard from Tehran suggested that “the circle of decision-making is narrowing … around the supreme leader and his military advisers.”

“The civilian national security leadership is not meeting,” she said. “The Foreign Ministry is not being consulted.”