(NEW YORK) — America’s main nuclear deterrent glides undetected under the oceans as it carries a cargo of ballistic missiles that will hopefully never be used.

Off the coast of Hawaii, ABC News visited the USS Maine, one of 14 Ohio Class U.S. Navy submarines capable of launching nuclear-tipped ballistic missiles.

Measuring two football fields in length and weighing 18,000 tons, the massive submarine carries 20 Trident 2 D5 missiles capable of striking targets up to 4,000 miles away.

Each missile is capable of holding up to 12 nuclear warheads — one reason why these submarines are able to carry about 70% of the nation’s active nuclear arsenal allowed by the New START Treaty.

“I’d say it’s the most powerful force in the world right now,” Vice Adm. Bill Houston, the commander of the U.S. Navy’s Submarine Forces, told ABC News.

But in keeping with U.S. policy, Houston could neither confirm nor deny whether there were missiles with nuclear warheads aboard the submarine.

You can see more of Martha’s rare access inside the sub and exclusive reporting on America’s nuclear defense this Sunday on a special edition of “This Week.”

Developed at the height of the Cold War with the Soviet Union, the submarines have continued with their classified missions, serving as a key part of America’s nuclear triad that includes strategic bombers and intercontinental ballistic missiles (ICBMs) housed in the western plains states.

Recent comments by Russian leaders about their strategic nuclear capabilities following the invasion of Ukraine have shined a spotlight on America’s nuclear deterrence mission.

Houston characterized comments by Russian leaders about Russia’s nuclear weapons capability as “very dangerous,” “irresponsible” and “unprofessional.”

“It gives more meaning to this mission,” said Houston. “But we view our mission as a peace mission, purely defensive is what we do.”

He added, “And so when they saber rattle, this deterrent here is meant to prevent that from occurring.”

A main part of why Ohio Class submarines are a powerful nuclear deterrent is because they are undetectable in vast stretches of ocean, making an adversary susceptible to a retaliatory strike should it carry out a strategic attack against the United States.

To stay hidden, the submarine will surface very rarely — if at all — during what could be a months-long patrol underwater.

“This submarine, once it’s underwater, it will not be detected,” said Houston. “It is the one portion of our deterrent that will always be available if needed.”

And maintaining that deterrent means that not even senior military leaders will know where the submarine is at any given time. That’s a privilege available only to the submarine’s senior leaders.

The crew will regularly train for the unthinkable, like the launch of nuclear-armed missiles in a retaliatory strike against a country that has carried out a strategic attack against the United States.

ABC News was allowed to witness a simulated launch exercise where redundancies are an integral security measure intended to ensure the validity of a presidential order to launch missiles.

“United States policy is not to aim our missiles at any adversary or any country,” said Cmdr. Darren Gerhardt. “If we said they’re targeted, they would be pointing to the spot in the ocean. They don’t go anywhere.”

Living with the Trident missiles is also a regular part of life for the 150 sailors on the submarine.

The sailors have to maneuver their way through hallways lined by 24 missile tubes that house ICBMs. The missiles are also located near the sleeping berths.

Crew members carry out their assignments in shifts with some gathering for breakfast at 3 a.m.

With the submarine operating hundreds of feet below the surface, the crew has little awareness about what is going on in the world. At times the submarine will come up to periscope depth to receive satellite signals for updates on what’s going on in the world. But that maneuver carries risk.

“But when I do come up to periscope depth that makes me vulnerable,” said Gerhardt. “So I have to minimize the amount of times I do that.”

And when the crew returns to their families, “we’re catching up on several months’ worth of information that we missed,” Gerhardt said.

Both Houston and Gerhardt said they’re used to this life under the sea.

“I would say this is where we’re more comfortable,” said Houston. “A pilot likes to be in the air. We like to be under the sea.”

Added Gerhardt, “This is our home.”

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(WASHINGTON) — When President Joe Biden arrives in Seoul on Friday, on his first trip to the region as president, he’ll be landing in a volatile region at a volatile time.

Biden will seek to shore up ties with regional allies and advance his vision of a free and open Indo-Pacific region, but he’ll do so as the threat of another nuclear test from North Korea looms.

At the same time, U.S. allies South Korea and Japan continue to squabble over historical grievances, blocking a breakthrough in bilateral relations.

Northern neighbor

Increasingly bellicose North Korea continues to paint itself as heavily-armed nation that its foes, including superpowers, should think twice about tangling with.

Images last month released by the official Korean Central News Agency showed the country’s leader Kim Jong Un overseeing a spectacular night parade in Pyongyang with soldiers marching in perfect formation and ICBMs.

“If any forces attempt military confrontation with the Democratic People’s Republic of Korea, they will be perished,” Kim reportedly vowed in a fiery speech.

Since 2021, North Korea has been steadily improving its missile technology, drastically increasing testing, including purported hypersonic missiles in January and a submarine-launched ballistic missile, or SLBM in May, and what is believed to have been a successful intercontinental ballistic missile test launch.

It was the first of its kind in years and Kim might very well have more ICBMs fired off during Biden’s visit.

In what has become the new normal, each test launch typically garners perfunctory rebukes from the U.S. and its allies, with Japan predictably condemning the act, lodging complaints with the U.N., and then vowing to share information.

Unsettling signs

Signs indicate the North is restoring tunnels at its Punggye-ri testing site, where all six North Korean underground nuclear tests to date have been conducted. In 2018, Punggye-ri was famously dismantled “in a transparent manner” in front of the world’s media. Now in 2022, a U.S. official tells ABC News that “the facility at Punggye-ri is capable of testing a nuclear device in short order.”

U.S. national security adviser Jake Sullivan told reporters Wednesday that U.S. “intelligence does reflect the genuine possibility that there will be either a further missile test, including long-range missile test, or a nuclear test, or frankly, both, in the days leading into, on, or after the president’s trip to the region.”

Sullivan said the U.S. was “preparing for all contingencies, including the possibility that such a provocation would occur while we are in Korea or in Japan.”

The Biden administration says the North “could be ready to conduct a test there as early as this month.”

Circling the wagons

Biden will visit both Japan and South Korea, two key regional allies with a history of icy relations. South Korea’s newly minted conservative president Yoon Seok-youl has called for a thaw.

Japan’s Prime Minister Fumio Kishida has said, “There has never been a time when strategic cooperation between the two nations, and between them and the United States, has been more necessary,” and says there is no time to waste in improving bilateral ties.

Despite the friendly overtures from the leaders of the two nations, experts say neither side is willing to make the first move to resolve the rows.

Jeff Kingston, director of Asian Studies at Temple University Japan, told ABC News the calls for unity are music to Washington’s ears.

“The U.S. wants its allies to cooperate in coping with contemporary threats but they have remained divided over their shared past. Improving relations will be a difficult process because history is very politicized in both nations,” he said.

Kingston said the recent failures of the two countries to see eye-to-eye is a wake-up call for those who have hopes that they could overcome the colonial past. “They also battle over territory — the Dokdo/Takeshima islets — and whatever else is handy.”

Jaechun Kim, professor of international relations at South Korea’s Sogang University, also has doubts fences can easily be mended.

Despite President Yoon’s signaling the desire for closer relations with Japan, he walks a tightrope, Kim said.

“There is limit to which he can be proactive here because if you’re seen as compromising on ‘history’ issues toward Japan, that is politically suicidal in the Republic of Korea,” he told ABC News.

Kim said Japan and Korea will have to have to find common ground somewhere.

“We should not expect or push for a breakthrough on history issues. That’s not realistic,” he said. “Rather, the two countries will have to deepen cooperation on issues where their interests converge, issues such as economic engagement and maritime cooperation in Indo-Pacific, and trilateral security cooperation between ROK, Japan, and the U.S. in Northeast Asia to augment deterrence and defense against North Korea’s nukes and missiles.”

ABC News’ Luis Martinez and Ben Gittleson contributed to this report.

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