WASHINGTON — The aircraft carrier USS Theodore Roosevelt is moving toward the waters off the coast of Yemen to prepare to intercept any potential Iranian shipments of weapons to the rebels fighting the U.S.-backed government of Yemen, a Pentagon official said Monday.

Col. Steve Warren, a Pentagon spokesman, said the carrier and ships supporting her had been in the Persian Gulf. They moved to the waters near Yemen because of increased instability there, he said.

The Roosevelt is also tracking a convoy of Iranian ships headed to the Gulf of Aden, said a Defense official speaking on condition of anonymity because they were not authorized to speak publicly about the Iranian vessels. The Iranians have been supporting Houthi rebels in Yemen.

The Pentagon has been tracking the progress of the Iranian ships since last week, the official said.

The Navy is prepared to intercept the ships, according to a second Defense Department official who was not authorized to speak publicly.

Moving the Roosevelt is viewed by the Pentagon as significant but not necessarily a prelude to conflict.

The Houthis are Shiite Muslims, while the Yemeni government has been dominated by Sunni Muslims.

Iran, which is also primarily Shiite, has been backing the Houthis, while Sunni nations, such as Saudi Arabia and the United Arab Emirates, are supporting the government.

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The guided-missile cruiser USS Normandy is accompanying the Roosevelt, the Navy said.