US Navy prepares to defend allies amid heightened tensions with North Korea

— -- Off the coast of the Korean Peninsula, U.S. and South Korean Navy ships prepared for an event they hope will never happen: a North Korean land and air attack against their neighbors to the south.

The annual bilateral training exercise called Maritime Counter Special Operations Force involved a U.S. aircraft carrier, the USS Ronald Reagan and a U.S. destroyer, the USS Stethem, as well as South Korean ships.

ABC News' Martha Raddatz was aboard the Reagan in the Sea of Japan for the exercise this week, as the Trump administration grapples with an increasingly hostile and technologically advanced North Korea.

Rear Adm. Marc Dalton, commander of Navy's carrier strike group in the Pacific, said the U.S. commitment to defending itself and its allies is "enduring."

"This exercise is an example of how we train with our allies in order to be ready to respond to a range of crises," he said.

North Korea's continued ballistic missile launches (14 this year alone) and a sixth nuclear test in September have instilled in the Reagan's crew the importance of their mission in bringing peace and stability to the region, Dalton told ABC News.

Interviews with the Reagan's top officers and pilots revealed the war of words between Kim Jong Un and President Trump, as well as North Korea's recent military actions, have little effect on the ship.

In the crew’s mind, it's all about being prepared, which makes exercises like the Maritime Counter Special Operations Force all the more important.

"This is what we have been training for," said Cmdr. Alex Hampton, who has flown with the U.S. Navy for 16 years. "Are we prepared for war? Absolutely. And I am confident in our abilities to execute anything that our nation command authority gives us to do."

Over the summer, North Korea demonstrated it has the ability to hit the continental United States with an intercontinental ballistic missile (ICBM).

Just this week, CIA Director Mike Pompeo told a Washington think-tank that North Korea could be just months away from perfecting the capability to attach a nuclear weapon to an ICBM.

But it's not just North Korea's technical advances that have thrust the regime into the international spotlight.

U.S. presidents have spent decades trying to counter North Korea's pursuit of nuclear weapons, but President Trump's blunt rhetoric toward Pyongyang has -- at times -- surprised U.S. allies.

In August, Trump said North Korean threats toward the United States would be "met with fire and fury like the world has never seen."

North Korea responded, saying the regime had plans to target Guam in "mid-August," though those plans were never carried out.

As for the 5,000 sailors on board the Reagan, they hope their mere presence off the Korean Peninsula can deter a North Korean strike that would surely escalate to war.

"By demonstrating our ability to defend ourselves, the idea is that we don't have to," Dalton said.

Watch ABC News’ "This Week" with Martha Raddatz Sunday for an in-depth look at U.S. Navy operations off the Korean Peninsula.

ABC News' Steve Turnham, Pat O'Gara and Justin Coleman contributed to this report.