MANILA, Philippines (AP) — Armed with extraordinary new U.N. sanctions, nations raced today to ensure North Korea’s biggest trading partners actually carry them out, an elusive task that has undercut past attempts to strong-arm Pyongyang into abandoning its nuclear weapons.

North Korea reacted angrily, vowing to bolster its arsenal and mount revenge against the United States. Foreign Minister Ri Yong Ho said Washington alone was to blame for the crisis and added his country was ready to “teach the U.S. a severe lesson” with its nuclear force.

“We will under no circumstances put the nukes and ballistic rockets on the negotiating table,” Ri said in a speech to an Asia regional gathering in the Philippines.

As President Donald Trump demanded full and speedy implementation of the new penalties, his top diplomat laid out a narrow path for the North to return to negotiations that could ultimately see sanctions lifted. Stop testing missiles for an “extended period,” Secretary of State Rex Tillerson said, and the U.S. might deem North Korea ready to talk.

“We’ll know it when we see it,” Tillerson said. “This is not a ‘give me 30 days and we are ready to talk.’ It’s not quite that simple.”

Even as they celebrate a diplomatic victory in persuading China and Russia to sign on to cutting new sanctions, the U.S. and other countries are deeply concerned that failure to rigorously enforce them could significantly blunt their impact. Since Saturday’s U.N. Security Council vote, Washington has put Beijing in particular on notice that it’s watching closely to ensure China doesn’t repeat its pattern of carrying out sanctions for a while, then returning to business as usual.