A nine-ship Iranian convoy believed to be laden with weapons bound for rebels in Yemen turned around Thursday after being followed by U.S. warships stationed in the area to prevent arms shipments, multiple sources in the Pentagon told Fox News.

The sources said the nine-ship convoy is south of Salalah, Oman, and now headed northeast in the Arabian Sea in the direction of home. The ships, which include seven freighters and two frigates, had sailed southwest along the coast of Yemen heading in the direction of Aden and the entrance to the Red Sea. The two Iranian warships escorting the convoy are Thondor Type 021-class missile boats and the other ships in the convoy are a mix of commercial vessels with some carrying shipping containers.

The USS Theodore Roosevelt, a 100,000-ton nuclear-powered aircraft carrier known as the “Big Stick” and her escort, the USS Normandy, a guided missile cruiser, have been shadowing the convoy for the past few days, the sources said.

Fighter jets taking off from the carrier have been relaying the convoy’s location to the U.S. Navy's higher command since the start of the week.

Pentagon officials say the U.S. Navy set up the nine ships in a line parallel to the coast of Yemen stretching from the Bab-el-Mandeb Straight to waters south of Oman, which provide “continuous coverage” of the Iranian convoy.

The Iranian Navy ships are characterized as "smaller than destroyers," a Pentagon official with knowledge of the convoy said Tuesday. Asked what type of weapons the freighters are carrying, one Pentagon official said, "they are bigger than small arms."

USS Theodore Roosevelt came within 200 nautical miles of the Iranian convoy, said Col. Steve Warren, a Pentagon spokesman.

"At all times we were monitoring the convoy, we didn't need to be in their wake," according to one official read in on the operation.

According to a Navy official the Iranian convoy never made it to Yemeni waters. “They turned around before they crossed the line extending from the Yemen/Oman border,” said the official.

But Pentagon officials remain cautious as the Iranian convoy continues on a northeasterly course off the coast of Oman in the direction of home.

"It's not over yet, we will continue to monitor them all the way back home," said one of the officials. 

Iran backs the Houthi rebels, who chased the Yemeni president from Sanaa and are fighting for control of the Gulf nation. Warships from Saudi Arabia and Egypt, who back Yemeni President Abd Rabbuh Mansur Hadi, are positioned to the southwest of the convoy, forming a blockade of the Gulf of Aden and the port city of Aden.

Western governments and Sunni Arab countries say the Houthis get their arms from Iran. Tehran and the rebels deny that, although Iran has provided political and humanitarian support to the Shiite group.

The U.S. also has been providing logistical and intelligence support to the Saudi-led coalition launching airstrikes against the Houthis. That air campaign is now in its fourth week, and the U.S. also has begun refueling coalition aircraft involved in the conflict.

The campaign meant to halt the rebel power grab and help return to office Hadi, a close U.S. ally who fled Yemen.

The defiant Shiite rebels pressed their offensive in the country's south on Thursday, apparently ignoring an overture from Saudi Arabia earlier this week, while the kingdom's warplanes continued to target their positions, officials said.

The rebels’ prized goal -- the port city of Aden -- remained an elusive one, in part thanks to the Saudi-led airstrikes.

Meanwhile, Pakistan's top leaders, including Prime Minister Nawaz Sharif and army chief Gen. Raheel Sharif, arrived Thursday in Saudi Arabia to push for negotiations in the Yemen conflict. The two are to meet with King Salman to discuss the crisis, according to Pakisitan's Foreign Office spokeswoman Tasnim Aslam.

Both predominantly Sunni majority countries, Saudi Arabia and Pakistan are close allies, and Islamabad has supported the Saudi-led coalition, though it declined to send troops, warplanes and warships to join it.

The kingdom and Gulf Arab allies launched the airstrikes March 26, trying to crush the Houthis and allied military units loyal to ousted President Ali Abdullah Saleh.

The Saudis believe the rebels are tools for Iran to take control of Yemen.

Loud explosions shook the cities of Taiz and Ibb in western Yemen on Thursday, as well as Aden when coalition warplanes bombed the rebels and their allies, witnesses said.

Residents also said the Houthis and Saleh's forces were attacking the city of Dhale, one of the southern gateways to Aden, with random shelling.

All Yemeni officials and witnesses spoke to The Associated Press on condition of anonymity because they were not authorized to talk to the media or feared for their safety amid the fighting.

The Associated Press contributed to this report.

Lucas Tomlinson is the Pentagon and State Department producer for Fox News Channel. You can follow him on Twitter: @LucasFoxNews