Gregg Zoroya

USA TODAY Opinion

One of the world's nuclear-armed nations boasted this month that it could obliterate New York City with a hydrogen bomb.

"All the people there would be killed immediately and the city would burn down to ashes," the state-run news agency reported.

The source? North Korea's government. The U.S. government's reaction? A shrug.

This is, after all, the isolated regime of leader Kim Jong Un that used the "b" word in February to describe South Korea's first female president, Park Geun Hye, or that years before labeled her predecessor, Lee Myung-bak, "a rat who should be struck down with a retaliatory bolt of lightning."

This is the government that threatened last summer to turn Seoul's presidential palace into a "sea of fire." In 2014, it vowed to fire nuclear-tipped rockets at the White House and Pentagon.

And that same year, it called for "divine retribution" against President Obama in a racist screed that characterized the American leader as a "dirty fellow ... a crossbreed with unclear blood."

State media: Kim Jong Un orders more nuke tests

The White House complained at the time that even by North Korea's standard for belligerent bombast, the comments about Obama were "particularly ugly and disrespectful."

Analysts say North Korea is talking tougher now in part because it feels it has the nuclear weapons to back up its threats.

Early Friday, North Korea fired a ballistic missile into the sea, South Korea said. It wasn't immediately known what type of missile was fired. This follows North Korea’s nuclear test in January, and its ballistic missile test last month.

"The larger that their arsenal gets, the more emboldened they are," said Jenny Town, assistant director of the U.S.-Korea Institute at the School of Advanced International Studies at Johns Hopkins University. "They're putting more things on the table now in terms of their responses and ratcheting up the rhetoric."

The country has devoted considerable resources to building nuclear weapons — estimate at 10 to 16 warheads — and is working on an intercontinental ballistic missile for delivering them.

"In recent years — and this is the big change — the regime has begun feeling confident enough to speak in one belligerent voice to all listeners," said Brian Myers, a professor at Dongseo University in South Korea who analyzes propaganda from Kim Jong Un's regime.

Photos: Life in North Korea

Angry and turgid bombast has flowed out of North Korea and its official state-run news agency for decades, dating back to the rule of Kim Jong Un's late father, Kim Jong Il, and his grandfather and founder of the nation, Kim Il-sung.

For a nation whose cultural development has largely remained stunted by decades of isolation, the florid language of official statements seems frozen in the stilted lexicon of the Stalinist era.

"The rhetoric is a product of isolation and decades of effort to assert political control through monolithic media messaging to the North Korean people," said Scott Snyder, senior fellow for Korean Studies at the Council on Foreign Relations. .

Still, those who study the regime say the pronouncements have grown even more belligerent and aggressive in recent years under Kim Jong Un, who took power in 2011 — not even 30 yet — with threats for the first time of pre-emptive nuclear strikes.

The defiant remarks typically emerge after new international sanctions or joint South Korean-U.S. military exercises. New United Nations sanctions were imposed early this month and Obama ordered new U.S. sanctionsWednesday.

Obama imposes more North Korea sanctions

Meanwhile, there were large, joint South Korea-U.S. military exercises this week.

Myers said the reasons for the overheated rhetoric are to maintain national pride in the regime's military prowess, but also to pressure the United States to show greater respect and even negotiate more directly with North Korea.

The U.S. government has held periodic talks and reached agreements with the regime, only to break off contact after North Korea violated the terms of the accords.

The irony, experts say, is after so many years of hyperbolic language, many other nations no longer take any of it seriously, Snyder said.

"The big challenge for North Korea I think from a Western perspective is that in the popular mind, Kim Jong Un has become a joke," Snyder said. "But he is developing deadly serious capabilities."