Donald Trump. Win McNamee/Getty Images

The back-and-forth between the US and North Korea has devolved into a full blown tit-for-tat as Washington and Pyongyang issue escalating, and competing, warnings.

Experts say Trump's rhetoric will likely prompt North Korean leader Kim Jong Un to double down further.

One expert said the rhetoric might heighten North Korea's fears that it is in a 'use 'em or lose 'em" position with respect to its missiles.

The back-and-forth between the US and North Korea that began with a Washington Post report about Pyongyang's ability to miniaturize nuclear weapons developed into a full blown tit-for-tat Thursday when President Donald Trump doubled down on his pledge to meet North Korea's threats with "fire and fury."

"The people that were questioning that statement, was it too tough? Maybe it wasn't tough enough," Trump said from outside his golf course in Bedminster, New Jersey.

"It's about time that somebody stuck up for the people of this country and for the people of other countries," Trump continued. "We're backed 100% by our military."

The president was responding to a statement issued by Pyongyang on Wednesday - which was itself a response to Trump's initial "fire and fury" remark - in which the Hermit kingdom threatened to attack Guam.

Just before Trump spoke to reporters on Thursday, North Korea warned in a new statement that the US would face "certain doom" if the US persisted as a "provocateur."

The escalating rhetoric is dangerous, experts say, because the situation is so unstable - one misstep could lead to the outbreak of war. Trump has also parted with his predecessors in his unwillingness to rule out a preemptive strike on Pyongyang, which has riled North Korean leader Kim Jong Un.

"For the North Koreans, as much as we tell ourselves that they're crazy, there is a credible defensive rationale to this nuclear program that they have been developing since the 1960s," said North Korea expert James Person, the director of the Hyundai Motor-Korea Foundation Center for Korean History and Public Policy at the Wilson Center.

"What the program is designed to do, in the North Koreans' mind, is to ensure their security and make sure they're not attacked," Person said.

By refusing to reassure Pyongyang that Washington is not seeking regime change or weighing a preemptive strike, however, Trump is giving Kim more reasons than ever to cling to North Korea's nuclear capability.

Reid Pauly, a PhD candidate in political science at MIT and predoctoral fellow at Harvard who researches nuclear proliferation, nuclear strategy, deterrence and assurance theory, said the "credibility of American military threats was only one contributor to the peaceful conclusion" of the Cuban missile crisis.

"The others were the Jupiter missile trade and, most importantly, an American pledge not to invade Cuba," Pauly explained.

"Fast forward to today, American power in the Western Pacific is not in doubt in Pyongyang. What is in doubt is the credibility of American and allied pledges not to intervene in North Korea. Until that fundamental security assurance is made credible, expect Kim to hang on to his nuclear deterrent," he added.

Timothy McKeown, a political science professor at the University of North Carolina whose research explores the determinants of nations' foreign policies, said that US mulling of preemptive nuclear strikes " might heighten North Korean fears that they are in a 'use 'em or lose 'em' position with respect to their nuclear forces."

"A classic conclusion of Cold War deterrence theory is that deterrence has failed the moment one or both sides conclude that war is inevitable," McKeown added. "Once that happens, the only interesting decision is when and how to begin, not whether to begin."

It remains to be seen whether the rhetorical tit-for-tat devolves into military action. But Pyongyang "is not suicidal," said Terence Roehrig, a professor of national security affairs at the US Naval War College.

"Pyongyang knows that any use of a nuclear weapon would mean the end of the regime," Roehrig said on Thursday. But he added that the use of force by the United States would be "incredibly dangerous" given the South Korean capitol's proximity to the North Korean border.

"We need to tone down the rhetoric and recognize that this is largely about deterrence," Roehrig said. "North Korea will continue to be deterred from an assault on South Korea as they have for the past 60-plus years, and Pyongyang's chief goal is to deter the United States from a regime-change operation."

NOW WATCH: Popular Videos from Insider Inc.