"I think the big concern here is miscalculation," Gen. Joseph Votel told reporters at the Pentagon. "I am concerned about rogue commanders, rogue Iranian Quds force naval commanders who are operating in a provocative manner and are trying to test us."
The Quds force is an elite unit within Iran's powerful Revolutionary Guard Corps (IRGC). The United States has blamed the IRGC ships for a series of naval confrontations in the Persian Gulf and Strait of Hormuz. Last week, a U.S. vessel fired into the water after an Iranian ship came within several hundred yards of a U.S. naval group, the latest in a series of close calls at sea.
Votel, who oversees U.S. military operations in the Middle East, said that close maneuvering by Iranian ships was not a novel phenomenon, but that the spate of recent incidents was worrying.
"What I see is this is principally the regime leadership trying to exert their influence and authority in the region," he said. "And they are trying to do it in provocative ways that are unsafe, unprofessional and really I think work against their — their objectives in the long term here."
The general said that most of the problematic maneuvers did not involve the regular Iranian navy, but instead were launched by the naval branch of the IRGC.
What U.S. officials fear most is that such an encounter will spiral out of control, leading ships to fire on each other and bringing far larger, more dangerous implications for two countries already at odds across the Middle East. Even in the wake of last year's landmark nuclear deal, the Obama administration has criticized Iran for its support to militant groups in numerous countries.
Tehran and Washington are on opposite sides of the wars in Syria and Yemen. In Iraq, they separately support the Baghdad government but remain at odds over Iranian-backed militias there.
Votel expressed confidence in U.S. naval might in the event that an escalation does occur at sea.
"Ultimately, we will prevail here," he said. "We certainly don't want that to come to pass, and that's why I call on them to act in a professional manner that they espouse to act, particularly in international waters."