Roundup: Iran confirms detention of 10 U.S. marines, Washington hopes for prompt return

Iranian troops have seized two U.S. Navy boats with 10 marines on board after the boats entered Iranian territorial waters in the Gulf, Iran's Revolutionary Guards said Wednesday.

"At 16:30 (1300 GMT) Tuesday, two American combat boats carrying 10 armed marines who had entered Iranian territory were seized by the combat units of the Guards naval force and moved to Farsi island," the Revolutionary Guards said in a statement.

The statement added that the U.S. marines are "in good health and being kept in a proper location."

"Passengers of the American boats, including nine men and one woman, (are being treated) with the Islamic conduct customary of the soldiers of the Guards naval forces," it said.

According to the statement, two aircraft carriers -- the USS Harry S. Truman and French Charles de Gaulle -- were both in international waters near Farsi island when the U.S. boats were captured.

Earlier in the day, Iran's semi-official Fars news agency reported that the two boats were captured by naval forces of Iran's Islamic Revolutionary Guard Corps near Farsi island, 2 km inside Iranian territorial waters.

Meanwhile, the NBC News quoted senior Pentagon officials as saying that it was unclear whether the American sailors who were aboard the small riverine boats, used by the U.S. Navy and Marines to patrol rivers and littoral waters, had strayed into Iranian territorial waters before they were captured.

The sailors were reportedly on a training mission moving between Kuwait and Bahrain around noon when their boats experienced "mechanical difficulty" and drifted into Iranian-claimed waters and were seized by Iranian Revolutionary Guard forces.

U.S. Secretary of State John Kerry has been on the phone with Iranian officials in an attempt to gain the release of the American sailors.

Iranian Foreign Minister Mohammad Javad Zarif assured Kerry that the sailors would be allowed to continue their journey promptly, a senior U.S. official said.

The official said the Iranians understood that it was a mistake and had agreed to release the Americans in international waters within hours, according to NBC.

White House spokesman Josh Earnest told U.S. media that the United States was monitoring the situation and "it's not entirely clear what happened."

He added that the sailors were safe and were expected to be released by the Iranians without a long delay.

Pentagon spokesman Peter Cook said the U.S. military, after contact with Iran, had received assurances that the American crew and the boats would be "returned promptly."

The incident occurred at a time when the United States is prepared to lift some of the sanctions on Iran in efforts to implement a historic deal reached last July on the Iranian nuclear program after prolonged diplomatic negotiations.

But new tensions have flared up recently after the United States slammed what they called Iran's "highly provocative" actions of firing unguided rockets last month near U.S. Navy ships in the Gulf including the USS Harry S. Truman aircraft carrier. Iran denied the accusation.

The incident also came hours before U.S. President Barack Obama, who has made the Iran nuclear accord a centerpiece of his foreign policy, was due to make his final State of the Union address to Congress and the public.

On Wednesday, the House was scheduled to vote on Republican-backed legislation that would give Congress greater oversight of the nuclear agreement, which Republicans have derided as a victory for Tehran. Endi