The Pentagon did not specify what exactly Colonel Susan Myers did but her dismissal, disclosed late on Thursday, followed publication of an email she wrote that questioned Vance's assertions during his visit to the base in March.
Vance had accused Denmark of failing to protect Greenland from "very aggressive incursions from Russia, and from China and other nations," without detailing the alleged aggression.
"I do not presume to understand current politics, but what I do know is the concerns of the US administration discussed by Vice President Vance on Friday are not reflective of Pituffik Space Base," Myers wrote, according to the news website military.com.
Reuters could not reach Myers for comment.
Trump has frequently said that the United States has a security imperative to acquire the island, which has been controlled by Denmark since 1721.
The Pentagon said she was fired due to a loss of trust and confidence.
Sean Parnell, a Pentagon spokesperson, wrote on X: "Actions to undermine the chain of command or to subvert President Trump's agenda will not be tolerated at the Department of Defence."
The Pentagon has been firing officers since Trump took office in January, in what appears to be a widening national security purge that has included the chairman of the Joint Chiefs of Staff, the top Navy admiral and the military's top lawyers.
Just earlier this week, the Pentagon also confirmed the firing of US Navy Vice Admiral Shoshana Chatfield, who holds a senior position in NATO. Chatfield's dismissal was first reported by Reuters.
Uniformed military officials are supposed to be loyal to the US Constitution and apolitical.
