U.S. Secretary of State Michael Pompeo warned against easing up on sanctions until North Korea gives up its nuclear weapons, drawing a rebuke from the regime that underscored how far apart the two sides remain almost two months after their leaders met in Singapore.

Back in Singapore for a regional security forum, Pompeo on Saturday called out Russia and China, highlighting reports that they are violating United Nations Security Council resolutions restricting trade with North Korea.

“We expect the Russians and all countries to abide by the UN Security Council resolutions and enforce sanctions on North Korea,” Pompeo said. “Any violation that detracts from the world’s goal of finally fully denuclearizing North Korea would be something that America would take very seriously.”

Nonetheless, Pompeo said he remains “optimistic that we will get this done.” In a later tweet, Pompeo said he had a “quick, polite exchange” with North Korean Foreign Minister Ri Yong Ho, adding that the U.S. delegation delivered a reply from President Donald Trump to a letter that North Korean leader Kim Jong Un sent to him earlier in the week.

Shortly after Pompeo flew out of Singapore after the meeting of the Association of Southeast Asian Nations, Ri read out a statement that set a far more confrontational tone and challenged the U.S. position that North Korea won’t get sanctions relief until it disarms.

The statement, similar to one that North Korea issued last month hours after Pompeo met North Korean officials in Pyongyang, accused the U.S. of demanding too much without offering anything in return and repeated the North Korean demand for “simultaneous actions” by the two sides.

“Impatience is not helpful at all for building confidence,” Ri said in the statement that was distributed to reporters. “Especially, advancing unilateral demands will further deepen mistrust instead of reviving trust.”

State Department didn’t immediately respond to a request for comment about the North Korean statement.

Mixed Messages

Since Trump met Kim in June, his administration has sought to show North Korea is moving toward giving up its nuclear weapons even as a steady stream of news reports say work is continuing on illicit programs. The mixed messages have undermined U.S. attempts to pressure North Korea, which hasn’t committed to a specific timetable for giving up its weapons.

While Pompeo has previously insisted that the bulk of North Korea’s denuclearization would take place within Trump’s first term, the statement from Ri suggested North Korea wants a longer time frame, citing a “Korean proverb which says ‘slow but surely’.”

After their summit in Singapore, the U.S. and North Korea agreed to four steps: establishing a new relationship, build a “lasting and stable peace regime,” work toward denuclearization, and return the remains of U.S. soldiers from the Korean War.

Anniversary Celebrations

In the statement, Ri accused the U.S. of focusing too much on the latter two points and ignoring the first two. He also said the U.S. was pressuring other countries not to attend celebrations in September to mark the 70th anniversary of the Asian country’s founding.

North Korea has continued to violate Security Council resolutions with illegal ship-to-ship transfers of petroleum and coal, Reuters reported on Saturday, citing a confidential UN report. It also said North Korea was cooperating militarily with Syria and looking to sell weapons to Yemen’s Houthis.

Pompeo on Saturday called on nations to halt any transfers of petroleum destined for North Korea, while also noting reports that Russia was granting permits for North Korean guest workers and allowing joint ventures in violation of UN sanctions. A Washington Post report earlier this week said North Korea is building at least one and perhaps more liquid-fueled intercontinental ballistic missiles.

Both China and Russia have denied violating sanctions, and said the UN should consider easing restrictions against North Korea after it suspended nuclear and ballistic missile tests.

The North Korean statement also contrasted with the State Department’s account of Pompeo’s encounter with Ri. According to U.S. spokeswoman Heather Nauert, Pompeo said the two should “meet again soon” and Ri responded, “I agree, there are many productive conversations to be had.”