Iranian Revolutionary Guard gunboats harassed three U.S. Navy warships in the Strait of Hormuz Sunday, in what U.S. military officials described as a "significant, provocative act."
Iran, for its part, described the incident as a mistake "that takes place every now and then" and that it was resolved.
Military officials told NBC News that two U.S. Navy destroyers and one frigate were heading into the Persian Gulf through the international waters of the Strait of Hormuz when five armed "fast boats" of the Iranian Revolutionary Guard approached at high speed, darting in and out of the formation.
At one point a radio message from one of the Iranian boats warned, "You are going to blow up within minutes."
The Navy warships went into defensive mode, radioed the usual warnings to steer clear, and in the end no shots were fired. U.S. military warships believe the Revolutionary Guard boats were "testing our defenses," the officials said.
White House, Tehran react
The White House warned Tehran against taking such actions in the future. "We urge the Iranians to refrain from such provocative actions that could lead to a dangerous incident in the future," White House spokesman Gordon Johndroe said.
Iranian Foreign Ministry spokesman Mohammed Ali Hosseini played down the incident, suggesting it was an issue of mistaken identity. He did not comment on the U.S. claims of the Iranian boats’ actions.
“That is something normal that takes place every now and then for each party, and it (the problem) is settled after identification of the two parties,” he told the state news agency IRNA.
The incident was “similar to past ones” that were resolved “once the two sides recognized each other.”
The United States expressed concern when the Revolutionary Guard forces took over Iranian naval operations in the Persian Gulf and Strait of Hormuz from Iran's regular navy more than five months ago.
However, Sunday’s incident was the first significant one since then.
Historical tensions between the two nations have increased in recent years over Washington's charge that Tehran has been developing nuclear weapons and supplying and training Iraqi insurgents using roadside bombs — the No. 1 killer of U.S. troops in Iraq.
In another incident off its coast, Iranian Revolutionary Guard sailors last March captured 15 British sailors and held them for nearly two weeks.
The 15 sailors, including one woman, were captured on March 23. Iran claims the crew, operating in a small patrol craft, had intruded into Iranian waters — a claim denied by Britain.