Iran navy
Iran's navy has reportedly conducted a drill in the Sea of Oman. Above, a Nour missile is test-fired off Iran's first domestically made destroyer, Jamaran, on the southern shores of Iran in the Persian Gulf, March 9, 2010. Reuters/Ebrahim Noroozi

A U.S. warship was warned to leave an area of the Sea of Oman where Iran’s navy was conducting military exercises Wednesday, Reuters reported. The news comes just weeks after 10 U.S. sailors were detained by Iran after entering the Islamic Republic’s territorial waters, in what American officials said was a navigational mistake.

Iran’s military drill Wednesday near the Strait of Hormuz, a crucial oil and gas trade route, reportedly included speedboats and submarines. The exercise was intended to bolster the country’s defenses against hypothetical enemies attempting to enter its waters, Iran's Tasnim News Agency reported. "It was predictable that the U.S. warship would approach the area to collect information on (our) military operations. So we warned them twice in the morning ... to keep their distance from the exercise area and keep clear of our missile range for their own safety," said Habibollah Sayyari, commander of Iran's fleet, according to media reports.

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This month, tensions briefly rose after a video surfaced showing Iranian rockets apparently being fired within 1,500 yards of two U.S. naval ships. The move was condemned by U.S. officials, including Cmdr. Kyle Raines, a U.S. Central Command spokesman, as being “highly provocative.” Iranians reportedly issued a warning 23 minutes prior to the missile launch. Days later, 10 sailors were detained after their ships strayed into Iranian waters. They were released Jan. 13 after being held overnight.

U.S. and Iranian relations have been tense since the 1979 Revolution, which ushered in today's Islamic government. Last summer, the U.S. and Iran reached a landmark agreement to help ease hostilities over Iran's nuclear program through placing restrictions on that program in exchange for a gradual lifting of sanctions against the country.

Iranian President Hassan Rouhani was visiting Europe as the naval drill was underway Wednesday. The president was expected to sign billions of dollars' worth of deals across Europe in an effort to boost economic ties after sanctions were rolled back this month. The trip marked the first official visit of an Iranian leader to Europe in 16 years.