The US military's Space Operations Command said Colonel Susannah Meyers had been removed from her duties at Pituffik Space Base due to a "loss of confidence in her ability to lead", AzVision.az reports, citing BBC.
Last month, Vance used a trip to the Arctic island to criticise Denmark - of which Greenland is a territory - for not spending more on security in the region, claiming it had "not done a good job" for Greenlanders.
The alleged email, released by a US military news site, told personnel that Vance's comments were "not reflective" of the base.
Following the trip, on 31 March, Col Meyers is reported to have written: "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."
Military.com - which published the email - said the contents had been confirmed as accurate to them by the US Space Force.
Appearing to confirm this was the reason for her firing, chief Pentagon spokesperson Sean Parnell linked to the Military.com article in a post on X, writing: "Actions [that] undermine the chain of command or to subvert President [Donald] Trump's agenda will not be tolerated at the Department of Defense."
The Space Force's statement announcing Col Meyers' removal on Thursday said that Col Shawn Lee was replacing her.
It added: "Commanders are expected to adhere to the highest standards of conduct, especially as it relates to remaining nonpartisan in the performance of their duties."
During his whirlwind trip, Vance had also reiterated Trump's desire to annex Greenland for security reasons.
Since the US delegation's visit, both Greenland and Denmark have shown a united front, opposing a US annexation of the autonomous Danish territory.
Earlier this month, Danish Prime Minister Mette Frederiksen's official visit saw her stand side-by-side with her Greenlandic counterpart Jens-Frederik Nielsen and his predecessor, Mute Egede.
Speaking to reporters, Frederiksen directly addressed Trump, telling him: "You can't annex other countries."
She added that Denmark was fortifying its military presence in the Arctic, and offered closer collaboration with the US in defending the region.
Greenland, the world's largest island, has been under Danish control for around 300 years.
Polls show that the vast majority of Greenlanders want to gain independence from Denmark - but do not wish to become part of the US.
Greenland has had the right to call an independence referendum since 2009, though in recent years some political parties have begun pushing harder for one to take place.
More about:
