SEOUL, South Korea (AP) -- America's No. 2 diplomat on Friday expressed sympathy for North Koreans facing hardships and food shortages linked to the pandemic, and renewed calls for the North to return to talks over its nuclear program.

North Korean leader Kim Jong Un has recently warned of a "tense" food situation and admitted his country faces "the worst-ever" crisis. But his government has steadfastly insisted it won't rejoin the talks unless Washington drops its hostility.

"We all feel for the people of the DPRK, who are indeed facing all the most difficult circumstances given the pandemic, and what it means as well for their food security," U.S. Deputy Secretary of State Wendy Sherman told reporters in Seoul, referring to North Korea's official name, the Democratic People's Republic of Korea.

"We only hope for a better outcome for the people of the DPRK," she said.

Sherman spoke after meeting South Korean officials, during which the two sides reaffirmed that they'll continue diplomatic efforts to convince North Korea to return to the nuclear talks.

"We are looking forward to a reliable, predictable, constructive way forward with the DPRK," Sherman said. "We have offered to sit and dialogue with the North Koreans, and we are waiting to hear from them."

Speaking beside Sherman, South Korea's first vice foreign minister, Choi Jong Kun, said, "We'll wait for a North Korean response with patience as now is the coronavirus period."

The talks between Washington and Pyongyang have made little headway since early 2019, when a second summit between Kim and then-President Donald Trump collapsed due to wrangling over U.S.-led economic sanctions. Kim has since threatened to bolster his nuclear arsenal and build more sophisticated weapons unless the Americans lift their hostile policy, an apparent reference to the sanctions.

Some experts say North Korea may be compelled to reach out to the United States if its economic difficulties worsen. Outside monitoring groups haven't reported any signs of mass starvation or social chaos in North Korea. In recent speeches, Kim has called for his 26 million people to brace for prolonged COVID-19 restrictions, indicating the country wasn't ready to reopen its borders despite the massive toll on its economy.

South Korea's spy agency told lawmakers this month that North Korea hasn't received any foreign coronavirus vaccine. COVAX, the U.N.-backed program to ship COVID-19 vaccines worldwide, said in February that North Korea could receive 1.9 million doses in the first half of the year. But UNICEF, which procures and delivers vaccines on behalf of COVAX, said recently that North Korea hasn't even completed the paperwork for receiving the vaccines and that it was unclear when they could be delivered.

After Seoul, Sherman is to travel on to Mongolia and then China, the North's last major ally and aid benefactor. She'll be the highest-ranking U.S. official to visit China since President Joe Biden was inaugurated in January.

During her visit to the northeastern Chinese city of Tianjin on Sunday, Sherman said she'll discuss North Korea with Chinese officials, saying Beijing "certainly has interests and thought" on it.

"The Biden administration has described our relationships with China as obviously a complicated one. It has aspects that are competitive, it has aspects where it is challenging, and aspects where we can cooperate," she said. "And thinking together about bringing the complete denuclearization of the Korean Peninsula is certainly an area for cooperation."

Choi said China knows well it can play "a very important role" in efforts to bring back North Korea to dialogue. He said Sherman's China trip would be "very meaningful" and that Seoul and Washington have a shared responsibility for Beijing to play its role.

Ahead of the meeting with Sherman, China has adopted a confrontational tone, reflecting the sharp deterioration in relations that began under Trump and continued under Biden.

The U.S. is "defining China as a competitor, provoking confrontation, and containing and suppressing China's development," Chinese Foreign Ministry spokesperson Zhao Lijian said at a daily briefing. "The U.S. side has been calling for dialogue with China from a position of strength, which only reflects its arrogance and hegemony."