A week before Donald Trump announced that he was scuttling a high-profile summit with Kim Jong Un, White House officials were “stood up” by their North Korean counterparts at a planned meeting in Singapore, according to a senior administration official.

During a conference call with surrogates on Thursday afternoon, Deputy Assistant to the President for Asian Affairs Matt Pottinger did not explicitly say that the non-connection in Singapore was directly responsible for Trump canceling the summit. But he painted it as a contributing factor to ultimately canceling the bilateral meeting.

“Unfortunately there’s been a succession of broken promises that have given the United States pause,” Pottinger said. The call was conducted on an off-the-record condition. However, The Daily Beast was not a party to the call and was briefed by a source who recounted Pottinger’s comments.

Pottinger revealed that the White House sent an advance team to Singapore–including at least one deputy chief of staff—to meet with the North Koreans and discuss logistics for the possible summit. “There they waited for three days,” Pottinger told conference callers. “The North Koreans never showed up. They never told us anything. They just stood us up.”

The silence persisted through the subsequent week until a North Korean official accused Vice President Mike Pence of being a “politically dummy.”

“Over the last six days the United States made numerous attempts to communicate with the North Koreans and they never responded to any of those efforts to communicate and to coordinate in advance of the 12 June summit,” Pottinger said.

Early Thursday, the White House released a letter from President Trump to North Korean leader Kim Jong Un lamenting the failure to agree on a summit and implicitly threatening the North with mention of the “massive and powerful” U.S. nuclear arsenal “that I pray to God they will never have to be used.”

Pottinger said that Trump dictated “every word” of the letter to Kim, a fact corroborated to The Daily Beast by another White House source.