EDITOR'S NOTE — Guided-missile submarines are the U.S. Navy's newest twist on underwater warfare, and among its most secret weapons. An Associated Press reporter was given exclusive access to one sub's first voyage since its makeover. Here is his report.

ABOARD THE USS OHIO — Capt. Andy Hale has just worked out and is still in a sweaty T-shirt and shorts as he stands in the battle command center. He is watching a flat-screen display that shows what's happening outside on the bow and the aft.

His billion-dollar submarine — the U.S. Navy's newest twist on underwater warfare — is hovering just below the surface off Guam as a submersible disappears into the dark waters, carrying a team of commandos.

The Ohio is the first of a new class of submarine created in a conversion from 1970s vessels by trading nuclear-tipped ICBMs for conventional cruise missiles and a contingent of commandos ready to be launched onto virtually any shore through rejiggered missile tubes — against conventional forces or terrorists.

The submarine's cruise across the Pacific comes as China builds its submarine fleet into the region's largest as part of the bulking up of its military. The voyage is the Ohio's first deployment since the makeover, and Hale is in the odd position of showing off the ship.

It's odd because the sub is all about stealth.

Hale can't talk about where the ship is going. The back of the ship, where the nuclear power plant is located, is off limits. The leader of the SEAL commando contingent aboard can't be named, and the commandos themselves can't be photo-graphed in any way that shows their faces.

But over the next few months, the Ohio will be making a very public statement, training intensively in some of the world's most crowded and contested waters and joining in exercises with America's Asian allies. Instead of hiding them, the Ohio will be showcasing its abilities to elude detection and operate too deeply and quickly to be tracked.

Then it will likely do what it does best — vanish.

"Submarines are the original stealth platform," Hale told The Associated Press, the only media allowed on board. "Submarine forces have always viewed the Pacific as a very important strategic area ... it's certainly grown in importance in the last 10 years."

Just about every country with a coastline in Asia wants or has subs.

China, Japan, Australia, India, Malaysia, Pakistan, Indonesia, Singapore, Bangladesh and South and North Korea either now have or are planning to acquire them.

Most don't pose much of a threat to the more advanced American fleet. But that is changing.

While Russia continues to be a factor, China now has the biggest submarine fleet in the region, with nearly 60. The U.S. has upped its presence in the Pacific, and now has more ships — and more subs — in this part of the world than in the Atlantic. But they are still outnumbered.

Two years ago, a Chinese sub shocked the U.S. Navy by surfacing within torpedo range of the USS Kitty Hawk aircraft carrier near the Japanese island of Okinawa. Beijing claimed the sub was in international waters and was not "stalking" the carrier, which was taking part in a naval exercise.

When the USS Ohio, which is based in Bangor, Wash., docked at Guam last month, China's official Xinhua news agency called the submarine a "warehouse of explosives" and a "devil of deterrence."

"If the Ohio turns west from Guam, it would need only hours to travel to the coastal waters of many Asian nations," it said. "The U.S. Navy believes the power of the cruise missile-armed nuclear submarine will be tremendous in a future war."

That is exactly what the Navy wants China and others to think, and why the Ohio is in the Pacific.

"The advanced capabilities that we have brought to this ship make it a premier front-line submarine," said the Ohio's executive officer, Lt. Cmdr. Al Ventura. "This has taken the submarine force to a whole new level."

The Ohio has both vast firepower and the ability to deploy quickly to wherever it's needed.

It has 24 launch tubes, 15 of which have been fitted for multiple Tomahawks — more than 100 in total.

That's more than were launched in the entire first Gulf War.

From an offshore position in the Pacific, it could strike Pyongyang, North Korea. From the Indian Ocean, it could hit anywhere in Afghanistan.