When I asked a senior official from Washington recently about the failure of the second Trump-Kim summit in Vietnam in late February, the response I received was every bit as diplomatic as I had expected.
"The US certainly thanks all countries who participated in our efforts to encourage North Korea to [agree to]complete, total and verifiable nuclear disarmament, and I wouldn't categorise the negotiation as failed since the fact is that the senior officials are talking and it is very encouraging," Joseph Felter, Deputy Assistant Secretary of Defence for South and Southeast Asia, told me during a visit to Bangkok.
"We hope to make progress and we are not going to give up," he said, while adding that any new reprocessing activity at North Korea's main nuclear site should "concern every nation".
That concern was underlined by satellite imagery taken on April 12 at the Yongbyon nuclear site and released by the Washington-based Center for Strategic and International Studies. It showed five specialised rail cars near the uranium enrichment facility and radiochemistry laboratory. This could be associated with reprocessing of radioactive material into bomb fuel, the centre said.
If true, then this reinforces observers' view that talks between US President Donald Trump and North Korean leader Kim Jong Un have failed to stop the North from making nuclear weapons.
Washington can continue to say, as Mr Felter did, that "the door is still open" for further negotiations as the US wants to pursue "a diplomatic solution", but Pyongyang has already adopted a stronger tone.
North Korea last week claimed it had tested a new tactical guided weapon and called for US Secretary of State Mike Pompeo to be replaced in negotiations between the two countries.
The Korean Central News Agency (KCNA) said Mr Kim had personally inspected and directed the test-firing, which acting US Defence Secretary Patrick Shanahan said did not involve a ballistic missile. However, it was North Korea's first public weapons test since the second summit, and analysts see it as a bid to increase Pyongyang's leverage.
Mr Pompeo visited North Korea four times last year and even met with the Supreme Leader himself. But he has fallen out of favour with Pyongyang after telling a US Senate subcommittee two weeks ago that he would describe Mr Kim as a "tyrant".
That prompted North Korean foreign ministry official Kwon Jong-gun to say that Mr Pompeo's "reckless remarks" had "unveiled his mean character". He blamed Mr Pompeo for scuttling the Hanoi talks, and said that if further talks take place, "I wish our dialogue counterpart would not be Pompeo but … [another] person who is more careful and mature in communicating with us".
Now we have to wait and see how Washington will respond, since it is clear that the North no longer trusts the leading American negotiator because he has displayed "gangster-like" ways in Pyongyang's eyes.
"We are aware of the report," a US State Department spokesman said in response to a reporter's query about Pyongyang's call for a replacement for Mr Pompeo. "The United States remains ready to engage North Korea in a constructive negotiation."
The signs do not look hopeful. North Korea's first vice-foreign minister, Choe Son-hui, last month threatened to abandon the negotiations. Now we have seen a new missile test, and Mr Kim is getting ready to meet Russian President Vladimir Putin. It could be said that the failure of the second summit is now haunting the US as it strives to denuclearise the North.
If the US gives in and changes its lead negotiator based on Pyongyang's request, it will definitely be seen as a sign of weakness. North Korea could also gain more leverage with help from another nuclear-power later this month, but that will depend on how Mr Kim and Mr Putin get along.
Abandoning the talks that Mr Trump initiated amid great fanfare would be an embarrassment that the billionaire president will certainly hate, and the worst-case scenario for everyone since it would put the world back at square one.
Either way, with or without more talks, a nuclear war would mean apocalypse for all of us, so I sure hope that Mr Felter is right on this one. We all need them to talk instead of pushing buttons.
"There may be future senior-level negotiations as we certainly want to pursue a diplomatic solution to this challenge that really affects all countries," he said.