North Korean leader Kim Jong Un may consider his atomic bombs a license to pursue hostile actions far short of nuclear war, security analysts said. Mutual nuclear capability raises the stakes for any kind of confrontation, and defense analysts and North Korea watchers worry that a miscalculation or rash action on either side could quickly escalate.
North Korea has a demonstrated history of provocative behavior, including a cyberattack on Sony Corp., the sinking of a South Korean warship and the shelling of a South Korean island.
"I worry if something like that happens, what is the risk of escalation?" said Ben Rhodes, who was deputy national security adviser to President Barack Obama. "If everybody is on tenterhooks, you have the type of incident that was manageable in the past suddenly explode."
North Korea said Wednesday that it is examining plans for firing missiles over the waters off Guam, home to U.S. military bases. Kim and President Trump also have exchanged threats and insults, including Trump warning of "fire and fury" if North Korea doesn't cease its threats, and Kim calling Trump "senile" in response.
Trump said Thursday that his comments may not have been "tough enough" and that "things will happen to them like they never thought possible."
Rhodes and others pointed to the 2010 sinking of the Cheonan warship, which killed 46 South Korean sailors, as an example of a conventional attack that would have more dangerous implications now.
"We're not, I think, in a real crisis right now," Rhodes said. "But the problem is, we've made the inevitable back and forth with North Korea feel much more risky."
South Korea blamed Pyongyang but did not retaliate with direct military action, and the international crisis abated.
The United Nations issued a statement condemning the attack but didn't name an alleged attacker; the United States said the ship was hit by a North Korean sub-launched torpedo.
Kim may calculate that his arsenal means he has even less to lose from such military actions, which do not involve nuclear weapons, and there is a risk that Trump might react to such an event in ways that heighten tension, said Jim Walsh, an Asia security expert at the Massachusetts Institute of Technology.
The current "bluster and bluffing" on both sides probably won't amount to much, he said, but is alarming nonetheless. Trump sends a message that he is "not serious" when he uses rhetoric such as the "fire and fury" threat, and he may need to send a very serious and unmistakable message to defuse a crisis later on, Walsh said.
"We are probably not going to get into a war with North Korea because the young Chairman Kim wakes up one morning and decides to come after the United States," he said. "But you can have war on the Korean Peninsula, and the main path to a war no one wants is miscalculation — little crises resulting in decisions no one wants to make."
North Korea's warning about Guam, where Secretary of State Rex Tillerson's plane refueled Wednesday, said it could create an "enveloping fire" around the Pacific island.
"Their rhetorical reaction was always going to be strong — it always is," said Evan Mederios, who directed Asia policy at the National Security Council.
Mederios said he worries that an emboldened North Korea could "mess around" on a new scale.
"Cyberattacks, more missile tests," Mederios said. "A sixth nuclear test is certainly in the cards."
Statements on Wednesday from Tillerson and Defense Secretary Jim Mattis appeared intended to dial down the rhetoric, even while issuing strong warnings to North Korea.
"I think Americans should sleep well at night, have no concerns about this particular rhetoric over the last few days," Tillerson told reporters aboard his plane home from an Asian tour dominated by the North Korean nuclear threat.
Mattis warned that the United States would win any war Kim might foolishly start.
"The United States is on the same page, whether it's the White House, the State Department, the Department of Defense, we are speaking with one voice," State Department spokeswoman Heather Nauert said Wednesday.
"The world is in fact speaking with one voice, and we saw that as it came out of the U.N. Security Council with a resolution that passed less than a week ago," Nauert said, referring to the unanimous U.N. vote Saturday in favor of tough new sanctions.