U.S. President Donald Trump has vowed that “pretty severe” things are in store for the North Korean regime should the country continue to press ahead with aggressive tests of its fledgling nuclear arms program. But military experts say the United States would be short on options in the event military strikes were deemed necessary, and warn those that exist are perilously risky.

“American options militarily are very limited and extremely dangerous, and I would say at this stage of the game should not be resorted to except under the most extreme and dire circumstance,” military analyst David Bercuson told CTV News.

Speaking in Poland on Thursday, Trump issued a stern warning to military leaders in the nation and called upon U.S. allies in the region to ramp up pressure on Pyongyang.

“They are behaving in a very, very dangerous manner, and something will have to be done about it,” Trump said. “I don’t like to talk about what I have planned, but I have some pretty severe things that we are thinking about.”

The U.S. heightened its military pressure on North Korea on Wednesday, engaging in a show of force with its South Korean alley following the launch of a North Korean intercontinental ballistic missile (ICBM) timed to coincide with the U.S. Independence Day holiday.

State media in Pyongyang now say North Korea has the power to strike the U.S. mainland with a nuclear warhead. Experts have said the missile is indeed powerful enough to put Alaska in range.

While Trump has made it abundantly clear that military actions are on the table, experts fear any attack on North Korean soil will cost an untold number of South Korean lives.

Seoul, home to some 10 million South Koreans, is within easy striking distance of North Korea’s devastating battery of conventional weapons massed along the demilitarized zone separating the two warring nations. North Korea’s estimated 8,000 artillery cannons and rocket launchers alone could rain up to 300,000 rounds on its southern neighbour in the first half hour of combat alone.

Bercuson estimates North Korean rockets and conventional artillery would easily overwhelm South Korean defence emplacements. Those living in the dense cities near the border would have mere minutes to reach whatever shelters are available.

“There is nothing there like the ‘Iron Dome’ that Israel used in their last war against Gaza,” he said. “There are some anti-missile emplacements, but nothing capable of intercepting the vast majority of artillery and rocket fire from the North.”

North Korea analyst Joseph Bermudez has narrowed down three main options for the Pentagon to disable North Korea’s striking capability, should the conflict escalate.

“None of them are really good,” he said.

Option one is a surgical strike. Bunker busting bombs delivered by air and sea to neutralize the country’s heavily fortified nuclear weapons and long-range missile facilities.

“The point of any surgical strike . . . is to strike out of the blue, so that it would mitigate the ability of (North Korea’s) civil defence to handle that,” said Bermudez.

Bercuson said such a strike would have to be done exclusively with precision guided weapons striking targets known to U.S. intelligence across the country, risking the possibility that some unknown weapons would slip through the cracks.

“You would still probably leave several sites untouched, and they would be retaliating against the civilians in South Korea,” he said. “We have a pretty good picture of where their stuff is, but you never have a perfect picture.”

The second option, according to Bermudez would directly target North Korean leader Kim Jong-Un with the hope that a successful strike would throw the regime into chaos for long enough to defuse the situation.

Of course, it is possible North Korea has detailed transfer of power plans for just such an occasion, and the odds of the U.S. acquiring sufficient actionable intelligence are slim.

“There is a low probability that a decapitation strike against Kim Jung Un would be effective. The reason being, he moves constantly,” said Bermudez.

He said the third, and most dramatic option, would encompass a sudden, overwhelming attack by U.S. fighter jets, bombers, missiles, and naval power to cripple the country’s vast military -- all-out war in other words.

The nuclear horse is out of the barn

Bercuson sees Trump’s recent sabre-rattling as the culmination of years of failed U.S. foreign policy aimed at stopping North Korea’s nuclear program. He says the time has come to accept that failure and move forward.

“At this stage of the game, you have to accept the fact that the horse is out of the barn. (Now) you do the best you can to make sure this doesn’t happen somewhere else, so that we don’t get a tenth country with nuclear weapons,” he said.

For all of its rhetoric, Bercuson wagers that even North Korea knows that putting its nearly complete nuclear arsenal to use would be a step too far.

“Let’s say North Korea develops 20 to 30 missiles with nuclear warheads on top. Are they going to attack the United States? I don’t think so. Any such attack would eliminate North Korea as an entity.”

Further economic sanctions and diplomacy are the options most experts are hoping the United States will pursue, given the high stakes and potential for massive civilian casualties.

With a report from CTV’s Mercedes Stephenson