SEOUL, South Korea (AP) — America’s top diplomat on Wednesday criticized North Korea’s human rights record and reiterated a vow to strip the country of its nuclear program, a day after Pyongyang warned Washington to “refrain from causing a stink” amid deadlocked nuclear negotiations.

U.S. Secretary of State Antony Blinken arrived in South Korea with Defense Secretary Lloyd Austin earlier Wednesday as part of their regional tour aimed at boosting America’s Asian alliances to better deal with growing challenges from China and North Korea.

“The authoritarian regime in North Korea continues to commit systematic and widespread abuses against its own people,” Blinken said at the start of his meeting with South Korean Foreign Minister Chung Eui-yong. “We must stand with people demanding their fundamental rights and freedoms and against those who repress them.”

Blinken called North Korea’s nuclear and missile programs “a threat to the region and to the world.” He said the United States will work with South Korea, Japan and other allies to achieve the denuclearization of North Korea.

How to get North Korea to return to talks was sure to be a major focus of meetings between Blinken and Austin and South Korean officials.

When Austin separately met his South Korean counterpart Suh Wook on Wednesday, he said their countries’ alliance “has never been more important” given “the unprecedented challenges posed by” North Korea and China.

The two top U.S. officials are to hold a joint “two plus two” meeting with Chung and Suh on Thursday in the first such contact between the two countries in five years.

U.S.-led diplomacy on North Korea’s nuclear program has been in limbo since a February 2019 summit between President Donald Trump and North Korean leader Kim Jong Un collapsed over disputes on U.S.-led sanctions. Kim has since threatened to enlarge his nuclear arsenal in protest of what he called U.S. hostility.

On Tuesday, Kim’s sister and a senior official in her own right, Kim Yo Jong, slammed the United States over its ongoing regular military drills with South Korea, which North Korea sees as an invasion rehearsal.

“We take this opportunity to warn the new U.S. administration,” Kim Yo Jong said in a statement. “If it wants to sleep in peace for (the) coming four years, it had better refrain from causing a stink at its first step.”

Some experts say Kim Yo Jong’s statement was a pressure tactic and that Pyongyang may try to further raise animosities with weapons tests to boost its leverage in future negotiations with Washington.

North Korea didn’t immediately react to Blinken’s comments Wednesday.

While in Tokyo on Tuesday, Blinken said that Washington reached out to North Korea through several channels starting in mid-February, but it hasn’t received any response. He said the Biden administration was looking forward to completing its policy review on North Korea in coming weeks and was looking both at possible “additional pressure measures” and “diplomatic paths.”

Blinken and Austin also joined forces with Japanese officials to criticize China’s “coercion and aggression” and reaffirm their commitment to ridding North Korea of all its nuclear weapons.

China on Wednesday said the U.S.-Japan statement “maliciously attacked” its foreign policy and seriously interfered in China’s internal affairs. Foreign Ministry spokesperson Zhao Lijian said China was “strongly dissatisfied and resolutely opposed” to the statement.

With North Korea's arsenal believed to be growing amid the deadlocked diplomacy, experts are debating over whether the United States and its allies should settle for a deal that would freeze North Korea’s nuclear program in return for relaxing sanctions — and possibly leave Pyongyang’s already manufactured nuclear weapons in place.

Shin Beomchul, an analyst with the Seoul-based Korea Research Institute for National Strategy, said he expects the Biden administration to pursue a deal with North Korea that resembles a 2015 accord that froze Iran’s nuclear program in return for lifting sanctions.

While the United States won’t likely give up its long-term commitment to denuclearizing North Korea, rolling back the country’s nuclear capabilities to zero is not a realistic near-term diplomatic goal, he said.

Trump blew up that 2015 Obama administration deal in favor of what he called maximum pressure against Iran, and the Biden government is trying to resurrect it.

In an op-ed in the New York Times in 2018, Blinken, then a managing director of the Penn Biden Center for Diplomacy and Global Engagement, argued that the best deal the U.S. could reach with North Korea “more than likely will look like what Barack Obama achieved with Iran.” He said that an interim agreement “would buy time to negotiate a more comprehensive deal, including a minutely sequenced road map that will require sustained diplomacy. That’s the approach Mr. Obama took with Iran.”

Other experts say an Iran-style deal won’t work for North Korea. Iran hasn’t built any bomb, but North Korea has already manufactured dozens. They say North Korea, which has a history of derailing agreements with its vehement rejection of verification processes, won’t find any reason to denuclearize when some of the most painful sanctions are lifted.

“Everyone can say easily that (settling for) a nuclear freeze would allow North Korea to preserve its existing nukes. But I ask them what other options do they have” to realize North Korea’s denuclearization, said Kim Yeol Soo, an analyst with South Korea’s Korea Institute for Military Affairs.

Another possible topic during this week's U.S.-South Korean talks is whether South Korea should actively participate in U.S.-led efforts to curb China’s rising strength in the region.

South Korea is a longtime U.S. ally and hosts about 28,500 American troops. But its economy is heavily dependent on trade with China, making it difficult to take any step deemed provocative to its biggest trading partner.

Suh, the South Korean defense minister, said Tuesday that the United States hadn’t formally proposed for South Korea to join an expanded format of the so-called “Quad” group that includes the United States, Japan, Australia and India, and that the Americans won’t likely make such a proposal during this week’s talks.