North Korea on Sunday lambasted the U.S. for shifting blame for the current lack of dialogue and frosty relations, saying that Washington’s top nuclear negotiator has turned down a recent invitation to Pyongyang.

The offer came after Sung Kim, U.S. special representative for North Korea policy, had displayed his willingness to meet with North Korean officials during his Asia tour last week. While in Beijing, the envoy said that while Washington was open to engagement and dialogue on the denuclearization issue, Pyongyang was not ready for “any serious and productive discussion.”

“The U.S. dismissed (the invitation) yet is trying to shift responsibility onto us by misleading public opinion, speaking as if no dialogue or contact is taking place because of our insincere attitude,” a spokesperson for Pyongyang’s foreign ministry said in remarks carried by the official Korean Central News Agency.

The spokesperson dismissed Kim’s demand for a “sincere attitude” toward denuclearization as an attempt to disarm the counterpart even before arriving at the negotiating table, which indicates in essence that the U.S. does not want dialogue.

The KCNA also lashed out at U.S. President Barack Obama for saying in a recent media interview that the regime will eventually collapse because of its deepening isolation and eventual information penetration.

“It marks the culmination of the U.S. shamelessness and hypocrisy that it is saying that the door is open for dialogue with us at a time when even its president is publicly making a fuss about toppling our system,” it added.

In an interview with a group of YouTube show hosts last week, Obama said it is “hard to sustain that brutal authoritarian regime in this modern world” and the ongoing influx of information would “bring about change” in the reclusive nation.

“The kind of authoritarianism that exists there, you almost can’t duplicate anywhere else. It’s brutal and it’s oppressive and as a consequence, the country can’t really even feed its own people,” he said. “Over time, you will see a regime like this collapse.”

During a recent inspection of joint naval and air force exercises, leader Kim Jong-un also launched a crude verbal attack, saying he would no longer sit with “rabid dogs” barking about overthrowing his government.

“We have no willingness to sit any longer with the rabid dogs openly barking that they will bring down (the government) by bringing about ‘changes’ to the socialist system,” he was quoted as saying by the KCNA on Saturday.

The country is ready to “counter any war including a war by conventional armed forces and a nuclear war,” Kim added.

With the war of words set to persist, North Korea is likely to toughen its stand against the U.S. especially as Seoul and Washington are gearing up to being their major annual military exercises ― Key Resolve and Foal Eagle ― later this month.

Washington brushed off Pyongyang’s offer last month of a moratorium on nuclear tests if it scraps plans for joint military drills with Seoul this year, warning against “implicit threats.”

With some 28,500 U.S. troops stationed in South Korea, the allies’ annual joint military programs, coupled with their strengthening criticism of Pyongyang’s human rights issues, have been incurring the wrath of the Kim dynasty, which sees them as an explicit challenge to its existence.

Tension is running high over the communist country’s suspected hack on Sony Pictures and human rights situation. Pyongyang has been dishing out intense criticism toward Washington via state media while flexing its military muscles in a series of drills.

The North and the U.S. are separately embroiled in a row over Pyongyang’s purported cyberattack on Sony, which released a satirical film late last year about a fictional assassination plot against Kim. The North’s state media on Saturday yet again denied its involvement, accusing Washington of “abusing its cutting-edge science and technology feats as weapons of war.”

For Seoul and Washington, their top concerns are a possible fourth underground blast or test-firing of an intercontinental ballistic missile by the North.

Any major new provocation will most likely freeze President Park Geun-hye’s renewed drive for better cross-border ties and unification preparations, while casting a further shadow over the prospects for a denuclearization of the peninsula and a restart of the related six-party talks.

To forestall such a crisis, South Korea is expected to step up efforts to reach out to its unruly neighbor, with reunions of separated families and other humanitarian issues weighing heavy on its agenda.

Pyongyang, for its part, has been making peace gestures toward Seoul since Kim expressed his openness toward an inter-Korean summit in his New Year speech. The South has also proposed high-level cross-border dialogue to discuss “all issues of mutual concern.”

Speculation is growing over whether Park would travel to Moscow and meet Kim this May, following news reports that the young leader accepted the Kremlin’s invitation to a ceremony marking the 70th anniversary of the defeat of Nazi Germany.

“There was a lot of talk about a fourth atomic test last year, so we made extensive diplomatic efforts to prevent it from becoming a reality. We are facing a similar situation this year,” a senior Seoul official said on condition of anonymity due to the sensitivity of the matter.

Another official said, “Given the ever-present technical demand for a fourth nuclear test, their decision (on whether or not to detonate a device) will ultimately hinge on political needs, which could be affected by various factors.”

By Shin Hyon-hee (heeshin@heraldcorp.com)