UNITED NATIONS — North Korea warned Monday that the unprecedented deployment of three U.S. aircraft carrier groups “taking up a strike posture” around the Korean Peninsula is making it impossible to predict when nuclear war will break out.

North Korea’s U.N. ambassador, Ja Song Nam, said in a letter to Secretary-General Antonio Gutteres that the joint military exercises with South Korea are creating “the worst ever situation prevailing in and around the Korean Peninsula.”

Along with the three carrier groups, he said, the U.S. has reactivated round-the-clock sorties with nuclear-capable B-52 strategic bombers “which existed during the Cold War times.”

He also said the U.S. is maintaining “a surprise strike posture with frequent flights of B-1B and B-2 formations to the airspace of South Korea.”

“The large-scale nuclear war exercises and blackmails, which the U.S. staged for a whole year without a break in collaboration with its followers to stifle our republic, make one conclude that the option we have taken was the right one and we should go along the way to the last,” Ja said.

He didn’t elaborate on what “the last” might be, but North Korea has launched ballistic missiles that have the potential to strike the U.S. mainland, and it recently conducted its largest-ever underground nuclear explosion. It has also threatened to explode another nuclear bomb above the Pacific Ocean.

The four-day joint naval exercises by the U.S. and South Korea, which began Saturday in waters off the South’s eastern coast, were described by military officials as a clear warning to North Korea. They involve the carrier battle groups of the USS Ronald Reagan, Theodore Roosevelt and Nimitz, which include 11 U.S. Aegis ships that can track missiles, and seven South Korean naval vessels.

WASHINGTON — Here’s a question rarely raised before Donald Trump ran for the White House: If the president ordered a pre-emptive nuclear strike, could anyone stop him?

The answer is no.

Not the Congress. Not his secretary of defense. And by design, not the military officers who would be duty-bound to execute the order.

As Bruce Blair, a former nuclear missile launch officer and expert on nuclear command and control, has put it, “The protocol for ordering the use of nuclear weapons endows every president with civilization-ending power.” Trump, he wrote in a Washington Post column last summer, “has unchecked authority to order a preventive nuclear strike against any nation he wants with a single verbal direction to the Pentagon war room.”

Or, as then-Vice President Dick Cheney explained in December 2008, the president “could launch a kind of devastating attack the world’s never seen. He doesn’t have to check with anybody. He doesn’t have to call the Congress. He doesn’t have to check with the courts.”

And the world has changed even more in the decade since, with North Korea posing a bigger and more immediate nuclear threat than had seemed possible. The nature of the U.S. political world has changed, too, and Trump’s opponents — even within his own party — question whether he has too much power over nuclear weapons.

These realities will converge Tuesday in a Senate hearing room where the Foreign Relations Committee — headed by one of Trump’s strongest Republican critics, Sen. Bob Corker of Tennessee — will hear testimony from a former commander of the Pentagon’s nuclear war fighting command and other witnesses. The topic: “Authority to order the use of nuclear weapons.”

Lockheed Martin continues to look at expand sales of the F-35 Joint Strike Fighter, with Germany, the United Arab Emirates, and now Saudi Arabia expressing an interest in buying the fifth generation aircraft. At the same time, though, there are increasing concerns that the aircraft’s centralized computer brain, known as the Autonomic Logistics Information System (ALIS), could pose threats to the capabilities and national interests of individual operators.

On Nov. 12, 2017, Defense News reported that Saudi Arabia is now seeking entry into the F-35 club. At the 2017 Dubai Air Show, American and Emirati officials have also confirmed that the UAE is in discussions with the United States about buying as many as 24 Joint Strike Fighters. These announcements followed reports earlier in November 2017 that Germany sees the stealthy fighter jet as the “preferred choice” to replace its aging Panavia Tornados.

“We in the UAE already live in a fifth generation environment,” Brigadier General Rashed Al Shamsi, deputy head of the country’s Air Force, explained at air show. “So acquiring the F-35 fighter jet is only a step forward to cope with the fifth generation mindset.”

It’s not entirely clear what Shamsi was referring to. At present, Israel is the only country in the Middle East that is part of the F-35 program and the only one actively seeking to acquire a fifth generation aircraft of any type.

Shamsi was most likely referring to the increasing proliferation of advanced surface-to-air missiles, especially the potential spread of Russia's S-400 system, and long range radars throughout the region. Iran, the UAE’s principle regional rival, continues to be actively seeking to improve and expand its integrated air defenses.