He reported this in testimony to Congress.
“The US is ready to resume constructive negotiations with North Korea on each of the four aspects of the joint statement in Singapore. Our goal is to achieve the final, fully verifiable denuclearization of the DPRK, which Chairman Kim (Jong-un) in Singapore has committed to do, ”RIA Novosti quoted the words of Stillwell.
Earlier, the North Korean Foreign Ministry said that Pyongyang did not intend to continue the dialogue with Washington until the United States took "practical measures to completely and irreversibly abandon the hostile policy regarding the DPRK."