North Korea said Thursday it will ignore a U.S. offer for talks unless it withdraws its hostile policy, after Washington reached out to Pyongyang in a bid to resume nuclear negotiations.

The statement by Choe Son Hui, the first foreign minister, came hours before the U.S. and South Korean foreign and defense chiefs met in Seoul for their first joint talks in five years to discuss North Korea’s nuclear program.

“What has been heard from the U.S. since the emergence of the new regime is only a lunatic theory of ‘threat from North Korea’ and groundless rhetoric about ‘complete denuclearization,’” Choe said, calling the offer for talks a “time-delaying trick.”

He reiterated North Korea’s position that no “dialogue of any kind” can be possible unless the U.S. rolls back its hostility. “Therefore, we will disregard such an attempt of the U.S. in the future, too.”

U.S.-led diplomacy focusing on North Korea’s nuclear weapons remains stalemated for about two years because of disputes over U.S.-led sanctions. Experts are debating whether the United States and its allies should settle for a deal that would freeze North Korea’s nuclear activities in return for relaxing sanctions to prevent its arsenal from growing.

Earlier this week, the powerful sister of North Korean leader Kim Jong Un threatened to abandon rapprochement with South Korea and warned the United States to “refrain from causing a stink,” while criticizing regular U.S.-South Korean military drills that her government views as an invasion rehearsal.

Choe again took issue with this month’s drills, saying that the United States “openly started aggression-minded joint military exercises targeting us.”

Some experts say North Korea, which is eager to win sanctions relief, may further raise animosities with missile tests to boost its leverage in any negotiations with the United States. North Korea’s moribund economy is under additional pressure because of the pandemic-related border closure that has significantly shrunk its external trade and a spate of natural disasters last summer.

U.S. Secretary of State Antony Blinken said during a visit to Tokyo earlier this week that Washington had reached out to North Korea through several channels, including in New York, 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.”

When Blinken met South Korean Foreign Minister Chung Eui-yong on Wednesday, he said the United States will work with allies to achieve the denuclearization of North Korea and criticized what he called North Korea’s “systematic and widespread abuses against its own people.” According to the State Department, Blinken and Chung also reaffirmed a shared commitment to address North Korean nuclear and ballistic missile issues that they said are “a priority for the alliance.”

Choe said U.S. attempts to contact North Korea included emails and telephone messages via various channels. She said that even on the eve of its drills with South Korea, Washington sent a message “imploring us to respond to its request through a third country.”

Choe said it will “only be a waste of time to sit with the U.S.”

Blinken and Defense Secretary Lloyd Austin are on the first overseas trip by Cabinet-level officials since President Joe Biden took office in January. Biden is pushing to restore alliances that were frayed under his predecessor Donald Trump’s “America First” approach and bolster a U.S. leadership on the world stage in the face of growing challenges from China.

Other likely topics during Thursday’s talks in Seoul include a U.S. desire to resolve historical disputes between Seoul and Tokyo and boost a U.S.-led trilateral cooperation, and South Korea possibly joining an expanded format of the Indo-Pacific group that involves the United States, Japan, Australia and India known as the Quad.