And returned to a hard line approach in the face of the storm of criticisms from the opposed interests in the US.
Allegedly a major failing of the talks was Pompeo's unresponsiveness to the proposal to have the US jointly declare an end to the Korean conflict on the anniversary of the Armistice. This would be a let down from the previous promise of "security guarantees," implied in Pompeo's CVIG formula. (Complete Verifiable Irreversible Guarantee of North Korean security.)
Some of the language in the official announcement from the North Korean foreign ministry is very similar to Kim Gae Kwan's apologia for Choi Son Hui published on May 24, 2018, which suggests that demands for unilateral nuclear disarmament from the US are a sensitive point for North Korea. ref: http://www.nkleadershipwatch.org/2018/05/25/kim-kye-gwan-issues-statement-on-us-dprk-summit/
On the other hand, North Korea backed off then and the summit went on. So Christopher Hill or whoever said it, was right, it's probably a negotiating tactic. It is also for domestic consumption in North Korea.
The North Korean foreign ministry statement reveals that the essential difference is still the same, the one bundle approach of the US, versus the step by step, reciprocal moves by both sides that the North Koreans want. However, the North should have taken a substantial step or steps after the US suspended military exercises. By unilaterally suspending the joint military exercises with South Korea, the US suggested implicitly that a tit for tat approach to building trust, and eliminating the nuclear threat could be managed. However, two things happened at the meeting in Pyongyang, Pompeo reverted to the CVID type approach, calling it FFVD, which is a distinction with only a nominal difference, and the North failed to reciprocate to the US South Korean suspension of military exercises, ironically criticizing it as "reversible." Pompeo's public statement in rebuttal of the gangster charge emphasized the one sided nature of the demand for denuclearization by the international community.