ABOARD THE USS PONCE (AP) — A new, key addition to American-led naval efforts to ensure Mideast oil keeps flowing has emerged as an unusual mix of a ship combining decades' worth of wear and tear with state-of-the-art technology and a largely civilian crew.

After winning a reprieve from the scrapyard, the USS Ponce was reborn through a rush retrofit earlier this year and turned into a floating base prowling the waters of the Persian Gulf. It is now getting its biggest workout since refurbishment as the centerpiece for sweeping anti-mine naval exercises under way that serve as a very public warning to Iran. The Islamic Republic has threatened to shut the Gulf's entrance at the Strait of Hormuz, the route for a fifth of the world's oil supplies, and would likely use mines to do so.

Anti-mine divers on practice drills deployed in small boats off the Ponce's stern gate early Saturday, and MH-53 minesweeping helicopters launched from the ship kicked up sea spray as they hauled mine-detecting equipment through the water. Later in the day, a U.S. destroyer pulled alongside, fighter jets roared past and gunners fired thunderous rounds from .50 caliber machine guns during a simulated encounter with a hostile vessel.

Senior Navy officials in the Gulf are quick to downplay talk of conflict with Iran, which is locked in a dispute with the U.S. and its allies over Tehran's disputed nuclear program. The West suspects Iran aims to develop a nuclear weapon; Tehran denies the charges.

U.S. military officials in the region insist the exercises, which include forces from more than 30 countries, are defensive and not directed at any country. They prefer to focus instead on the Ponce's role as an innovative new tool to help ensure security in the region, and on the need to train with allies to keep sea lanes open.

Still, the message is clear.

"Any extremist group, any country that puts mines in the water would be cautioned" by the exercises, said Marine Gen. James R. Mattis, the U.S. Central Command chief, during his first visit onboard the Ponce since it deployed June 1. "We do have the means to take mines out of the water if they go in. We will open the waterways to freedom of navigation."

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Military leaders believe the Norfolk, Va.-based Ponce is central to that mission.

More than half the length of most U.S. aircraft carriers, the Ponce can accommodate multiple helicopters on deck and small boats in a well deck below.

The ship was originally an amphibious transport dock built at the height of the Vietnam War. Those types of vessels are typically used to carry landing forces of Marines.

It's now known as the Navy's first "afloat forward staging base-interim," a name given because the Ponce is meant to be a stopgap until a similar base built from scratch is delivered. That won't happen until at least 2015.

"This will more or less act as a test for using floating platforms in the sea for military operations," Riad Kahwaji, chief executive of the Dubai-based Institute for Near East and Gulf Military Analysis, said of the reconfigured Ponce. "There'll be a lot of defense industry officials observing the performance of this."

Much of the original ship remains, including the tight Marine-style bunks stacked four high from floor to ceiling in some parts of the ship. But there are plenty of 21st Century additions too.

Berths for around 100 people were removed and replaced with a high-tech joint operations center, where streaming video and data feeds can be shown on flat-screen displays.

Powerful MK-38 guns installed during conversion include remotely controlled digital cameras that let operators zoom in on far-off targets of interest. And a ScanEagle surveillance drone launched from and recovered by the ship keeps an eye on the sea for miles around all day long.

In its new role, the Ponce is initially intended to be a close-to-the-action support hub for mine-clearing ships, coastal patrol vessels and helicopters. Ships can take on fuel and supplies without having to return to port, and a wide range of repairs can be handled by machinists onboard. That means far less downtime for minesweepers and other vessels using the Ponce as a stopping-off point, according to analysts and Navy officials.

The Ponce's Spartan accommodation can also handle hundreds of additional personnel, such as the French anti-mine divers in distinctive camouflage shorts currently onboard. In theory, special operations forces could also fill bunks aboard the Ponce, which is able to launch the small boats and helicopters they often use.

There is also the benefit of not needing to secure approval from allied countries where U.S. troops are based before conducting operations from an offshore staging base such as the Ponce.

"A country that's believed to be friendly to the U.S. could overnight become hostile to the U.S., and this could pose a threat to U.S. operations," Kahwaji said, citing recent violence directed at American embassies in response to an anti-Islam film.

Although it is under the command of a Navy captain, most of the Ponce's crew are civilians. It has more than 155 civilian crew members from the Military Sealift Command and 55 Navy sailors, according to the ship's commanding officer, Capt. Jon Rodgers. The number of civilian crew can fluctuate depending on who is onboard.

The MSC is normally responsible for running about 110 supply ships and other non-combat vessels for the Navy, but the Ponce's hybrid crew is unusual.

Visitors arriving by helicopter are met on the flight deck by some crew in uniform and others in civilian coveralls. Civilian employees keep the floors and toilets clean, and dish out corned beef hash and French toast on the mess deck. Some of the MSC crew members have dreadlocks — a no-no for enlisted sailors — and many are in their 40s or beyond. A handful are older than 60.

It's not just the civilian crew that's showing its age. The Ponce is among the Navy's oldest ships. Construction began in 1966, and it was commissioned during the Nixon administration in 1971.

Rust is prevalent throughout the ship, and many of the fittings retain a Cold War feel.

"Just walk around and you can see," said Kevin Chavis, 45, a retired Navy electronics specialist from Brooklyn who is now part of the Ponce's civilian crew. "Yeah, it's old. But just like a car, if you change the filters and the oil, it'll keep running."