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The unpredictable North Korean regime issued more threats and a rare offer to engage in talks Thursday, the day Otto Warmbier's family buried their son and amid increasing tensions on the peninsula.

The events showed the schizophrenic nature of the rogue nation's foreign policy, and highlighted the challenges faced by countries seeking to rein it in. But the offer to engage in talks with the U.S. was as close to an olive branch as North Korea has extended in recent memory - and it came along with a simultaneous threat.

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Kim Jong Un has made his nation even more isolated than it was under his father.

"Under certain circumstances, we are willing to talk in terms of the freezing of nuclear testing and missile testing," North Korea Ambassador to India, Kye Chun Yong, told India's TV network WION on Wednesday.

Under certain circumstances, we are willing to talk in terms of the freezing of nuclear testing and missile testing."

— Kye Chun Yong, North Korean ambassador to India

When asked if he was open to talk with the United States at “any time,” he simply responded, “yes.” He said if their demands are met “we can negotiate in terms of the moratorium of such as weapons testing.”

The negotiations, he said, must come without preconditions from Washington.

“For instance, if the American side completely stopped big, large-scale military exercises temporarily or permanently, then we will also temporarily stop,” Kye added.

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FILE - In this Feb. 29, 2016, file photo, American student Otto Warmbier speaks as he is presented to reporters in Pyongyang, North Korea. More than 15 months after he gave a staged confession in North Korea, he is with his Ohio family again. But whether he is even aware of that is uncertain. (AP Photo/Kim Kwang Hyon, File) (Warmbier served 17 months of a 15-year sentence before he was sent home in a coma-like state. His funeral was Thursday.)

Yet, on Thursday, the hermit regime stepped up their rhetoric against the U.S.

"The army of the DPRK is whetting the sword of retaliation shaper [sic] than before with a firm hold on the nuclear sword of justice to cope with the U.S. imperialists' escalating aggression moves," according to a posting on the Korean Central News Agency website.

They went on to say, according to KCNA watch, “We have already recommended and warned the U.S. several times enough to be understandable. However, the Trump administration, obsessed by megalomania, is going arrogant to mount a preemptive nuclear strike at the DPRK.”

This posting was published the same day that the family of 22-year-old Warmbier buried their son. He died a week after Pyongyang returned him to his family in a coma-like state after being held in a North Korean prison, serving what was supposed to be a 15-year sentence of hard labor.

“The United States once again condemns the brutality of the North Korean regime as we mourn its latest victim”, President Trump said in a statement.

Just hours after Warmbier’s funeral, Congressmen Adam Schiff, D-Calif., and Joe Wilson, R-S.C., announced the “North Korea Travel Control Act,” which would require the Treasury Department to issue regulations requiring a license for travel to, from, and within North Korea by American citizens, and ban tourist travel by Americans. The Schiff-Wilson bill is expected to be considered in Committee in the coming weeks.

The North Koreans, who have shown no remorse over Warmbier’s death, are reportedly pouring resources into a well-known nuclear testing site, possibly preparing for their sixth nuclear test.

Sebastian Gorka, deputy assistant to President Trump, told Fox News “North Korea remains an incredibly aggressive nation. It is threatening the stability of the whole region."

Gorka also called for China to clamp down on North Korea, as it accounts for more than 80 percent of trade with the rogue nation.  On Tuesday, however, President Trump tweeted, "While I greatly appreciate the efforts of President Xi & China to help with North Korea. it has not worked out. At least I know China tried!"

The administration is considering new sanctions against Pyongyang and wants Beijing to agree to them.

On Wednesday, Secretary of State Rex Tillerson and Defense Secretary James Mattis held a joint press conference after meeting with Chinese officials to discuss the situation with North Korea.

"We reiterated to China that they have diplomatic responsibility to exert much greater economic and diplomatic pressure on the regime if they want to prevent further escalation in the region," Tillerson told reporters.

Mattis said the two sides affirmed North Korea's nuclear and missile programs are a threat to peace and security in the region, adding that the United States "will continue to take necessary measures to defend ourselves and our allies."

That same evening, at a rally in Iowa, President Trump said that the U.S. has "a very good relationship with China and I do like President Xi," but added "I wish we would have a little more help with respect to North Korea from China, but that doesn't seem to be working out."