"This is a decades-long challenge, getting the North Koreans to make a fundamental strategic decision, which is that the nuclear weapons they possess today frankly present a threat to them and not security", said Pompeo, CNN reported.
Kim meeting Trump fulfilled an important foreign policy goal for North Korea, and China, its main trading partner, has been observed resuming trade with Pyongyang.
Trump's comments echoed the stance of Republican senator Lindsey Graham, who said Pyongyang's latest condemnation of the US has "China's hands all over" it.
The United States' annual August military drills with South Korea canceled last month by order of President Donald Trump as his administration negotiates a halt to North Korea's nuclear program would have cost the Pentagon about $14 million, according to defense officials.
The remains of almost 8,000 US troops remain unaccounted for on the Korean peninsula, and 5,300 of those bodies are believed to be located somewhere north of the demilitarized zone. Kim Jong-un vowed to push forward with the "complete denuclearization of the Korean Peninsula" in a statement signed alongside President Trump, but never clarified what that statement meant.
North Korean dictator Kim Jong-un in a potato field.
The two sides did agree to eventually hold a summit in 2018. "But, it seems that the USA misunderstood our goodwill and patience".
Pyongyang has already sent back the remains of 200 US troops, and the director of a USA defense agency said he is hopeful improved relations with North Korea will result in more recoveries.
"Kim has played Trump like a Stradivarius".
Trump told reporters Tuesday that he might have another gift for Kim as well.
"Just heard Foreign Minister of North Korea speak at U.N. If he echoes thoughts of Little Rocket Man, they won't be around much longer!"
While China may be genuinely committed to pushing Pyongyang to denuclearize, it'll inevitably bear the brunt of any back-and-forth from North Korea's delivery, according to Tsai Tung-Chieh, a professor of global politics at National Chung Hsing University in Taichung, central Taiwan.
On Monday, Trump addressed the dispute on Twitter.
The Trump administration's latest announcement to slap tariffs on an extra $200 billion of Chinese imports has sparked an outcry from China, whose commerce ministry said on Wednesday the US move is "unacceptable" and hurts America's own interests, China and the rest of the world.