Several officials accepted and then canceled at the last minute. They included acting Secretary of Homeland Security, Kevin McAleenan, who stayed in Washington to testify Thursday to a House panel about the situation at the U.S. border.
The Trump administration has portrayed developments at the U.S.-Mexican border as a top national security threat, but the topic was barely raised at Aspen.
McAleenan may have wished he was enjoying Aspen's cool conditions instead of facing heated questions from Rep. Alexandria Ocasio-Cortez of New York and House Oversight Committee Chairman Elijah Cummings, who grilled him about the treatment of migrants in U.S. detention facilities. "We're doing our level best," McAleenan told the lawmakers.
Some administration officials did attend, though. The most senior was Sigal Mandelker, the undersecretary of the Treasury for terrorism and financial intelligence. She sparred civilly on Friday with Wendy Sherman, a former State Department undersecretary who helped negotiate the Iran nuclear deal that Trump abandoned. Amy Hess, executive assistant director of the FBI's criminal, cyber response and services branch, also spoke on Saturday.
Among others in attendance included Philip Davidson, head of the U.S. Indo-Pacific Command, and Robert Ashley, the director of the Defense Intelligence Agency. John Rood, Under Secretary of Defense for Policy, also spoke on Saturday.
But there was, among participants, a distinct feeling of being let down. Officials may have stayed away out of fear for hurting their careers: Coats remains in his job, but has faced speculation for months that Trump wants him gone, in part because of his remarks a year ago.
The absences were also a reminder of how many officials occupy key posts in the Trump administration on an "acting" basis.
Some conservatives complained they were invited only to provide token opposition. Other potential invitees were told to stay away because administration officials felt the 2018 conference was too anti-Trump, according to a person familiar with the matter who asked not to be identified.
"There has long been an insular phenomenon in foreign policy circles where a few Washington types go to conferences to speak to a few more Washington types," Richard Grenell, the U.S. ambassador to Germany said by email, describing a larger issue. "The latest trend is to shrink the circle even more by having Washington types discuss issues with just one side of the political aisle."
While Trump and most of his team didn't show up, the president was on everyone's mind. As panelists discussed a resurgent Russia's implications for European security, Trump continued to rage against four congresswomen of color. And as the sun rose in a cloudless sky on Friday in the Roaring Fork Valley, Trump unloaded on New York Times foreign affairs columnist Thomas Friedman -- who spoke at the forum as recently as 2018 -- whom he called "the Chin" and "a weak and pathetic sort of guy."