To anyone fearing nuclear warfare following the radioactive rhetoric of U.S. President Donald Trump and North Korean leader Kim Jong-un, take comfort: None of the hallmarks of impending military conflict is visible.

Not yet, at least.

Defence analysts and experts on the Korean Peninsula are watching for potential telltale signs of an advancing skirmish such as the movement of U.S. forces in the Asia-Pacific region.

They doubt the escalating war of words will become a real shooting war. Meanwhile, Guam has not changed its threat levels, despite the U.S. island territory's waters being a stated target of Pyongyang.

Trump has kept up his ominous tone, tweeting a warning on Friday that "military solutions are now fully in place, locked and loaded."

Should it come to that, Harold Kazianis, director of defence studies at the Center for the National Interest, was unequivocal.

A U.S. Army Paladin self-propelled howitzer takes part in a military exercise near the Demilitarized Zone separating the two Koreas in Paju, South Korea on Friday. Defence analysts doubt the escalating war of words between the U.S. and North Korean leaders will become a real shooting war. (Kim Hong-Ji/Reuters) "All the military options are horrific."

Mainstream analysts agree there's no attack plan that would avoid the deaths of millions, though Kazianis said the chances of full-bore war breaking out remain "below the threshold of sheer panic."

That could change with hints at a possible unilateral U.S. strike, telegraphed by a buildup of forces and an armada of warships, advanced attack submarines and aircraft carriers to the region, as well as jets screeching toward the peninsula.

"What you'd see is a surge in air assets — B-1 bombers, B-2 bombers, F-22 stealth fighters — and you'd see these things coming a mile away," Kazianis said.

The movement of troops, military equipment and supplies into the region may not mean conflict is imminent, but it would at least signal resolve.

A worst-case scenario

The danger, Kazianis said, is that Kim would also be alerted to a U.S. show of force, and in a worst-case scenario, suspicions of an intended surgical strike on his nuclear assets could prompt him to unleash everything he can at U.S. allies.

"That's firing up to 60 nuclear weapons, 130 chemical weapons, and biological weapons down on South Korea. A nightmare scenario, with 10,000 artillery tubes pointed at Seoul, one of the world's biggest cities."

While the leader of a nuclear-armed North Korea may realize he can't best the U.S. militarily, Kim "knows he can still take millions to the graveyard," Kazianis said.

Andersen Air Force base stands on Guam, a U.S. Pacific Territory. There has been no move to organize emergency departures for U.S. diplomats, their families or other American citizens from areas threatened by North Korea. (Erik De Castro/Reuters) Such a scenario still seems improbable to experts, who say what's notable beyond the torqued-up rhetoric has been a lack of action.

Were the U.S. to be taking these threats seriously, for example, one of its first manoeuvres would likely be a mass evacuation of American civilians from South Korea, where 20,000 troops are based, as well as thousands more from Japan, said Derek Chollet, a former Obama administration official and senior adviser for security and defence policy at the German Marshall Fund in Washington.

Chollet, who was in the government during the Libyan revolution, recalled the scramble to organize emergency departures for U.S. diplomats, their families and other American citizens, "to the point that we, the U.S. government, hired a ferry for them to pack up and leave on."

If the situation in the Korean Peninsula intensifies, he suggested airlines could close their routes and be called upon to assist in emergency evacuations, along with military aircraft.

Chance of war is 'fairly low'

There's no inkling that kind of operation is about to happen any time soon, said Lisa Collins, a fellow in the office of the Korea Chair at the Centre for Strategic and International Studies.

"The chance of us engaging in a war with North Korea, under the current circumstances, is fairly low," Collins said. "Both North Korea and the U.S. know very well that any pre-emptive strike or military action would result in an immediate response by the other side that could quickly escalate into an all-out war."

Most people have wrongly played the Kim family as being mad or irrational. — Defence analyst Stephen Noerper

Along with an expected military buildup and evacuations, Collins said, a strong signal of serious debate in the Oval Office about ordering the use of force against North Korea would be leaked reports.

"You would expect to see leaks about discussions about the president's ability to authorize use of force against North Korea, whether Trump has the power to do what he wants without Congress's approval," she said.

south Koreans use a subway whose entrance bears a shelter sign in Seoul on Friday. A North Korean attack would be 'a nightmare scenario, with 10,000 artillery tubes pointed at Seoul, one of the world's biggest cities,' says military analyst Harold Kazianis. (Kim Hong-Ji/Reuters) That was, as Collins pointed out, the pattern in the lead-up to the 2011 military intervention in Libya and the 2003 invasion of Iraq.

Meanwhile, long-planned joint military drills set for Aug. 21 to 31 by the U.S. and South Korea are to go on as scheduled.

The exercises would overlap with the North's declared plans to launch four missiles within 30 to 40 kilometres of Guam, leaving open an alarming possibility for error that could spiral into warfare, said Kingston Reif, director for disarmament and threat reduction policy at the Arms Control Association.

"If the two sides aren't careful and don't seek to de-escalate tensions, the greater the potential for a mishap or overreaction that could get out of control."

A woman in Seoul walks past a broadcast showing images of a North Korean missile launch this year. The South Korean president said Monday that the country would do whatever necessary to prevent open war on the Korean peninsula. (Lee Jin-man/Associated Press) The explosive potential for miscalculation worries Stephen Noerper, senior director for policy at the Korea Society.

Even so, what could prevent an all-out war is Kim's awareness of the "asymmetrical nature" of a potential toe-to-toe fight between his isolated nation and the military behemoth that is the United States. Kim's brutality toward his own people and his unhinged rhetoric shouldn't conceal his pragmatism and a fundamental interest in the survival of the regime, said Noerper, who teaches at Columbia University.

'Walk to the line and walk back'

"Most people have wrongly played the Kim family as being mad or irrational," due in part to their "cultish personal proclivities," he said. "But his primary concern is regime security. A conflict would be an endgame in which the regime disappears. So the idea is they walk to the line and walk back."

The pattern of sabre-rattling and retreat has gone on for decades. It's expected this time should go no differently, though the wild card is the new U.S. president's knack for bombastic sound bites.

Diplomacy is still possible. The U.S. has reportedly continued to use a secret back-channel communication line with North Korea. Preserving that line could be crucial, though the president runs the risk of undercutting the efforts with tough posturing.

As Trump told reporters on Thursday: "We don't want to talk about progress, we don't want to talk about back channels. We want to talk about a country that has misbehaved for many, many years … and I had no choice but to take it on."