WASHINGTON, United States - The discussions come as Musk has been embroiled in public spats with Ukrainian leaders who were angered by his controversial plan for de-escalating the conflict, which included acknowledging Russian sovereignty over Crimea.
Starlink, a constellation of more than 3,000 small satellites in low Earth orbit, has been vital to Ukraine's communications as it fights against Russia's invasion, with SpaceX donating some 25,000 ground terminals, according to an updated figure given by Musk last week.
In a series of tweets, the world's richest man appeared to confirm a report by CNN saying he had written to the Pentagon warning that his financial contributions would come to an end, and that the military would need to foot the bill.
"SpaceX is not asking to recoup past expenses, but also cannot fund the existing system indefinitely *and* send several thousand more terminals that have data usage up to 100X greater than typical households," he tweeted.
"This is unreasonable."
Musk said the operation has already cost SpaceX $80 million and is projected to exceed $100 million by the end of the year.
But CNN said SpaceX figures shared with the Pentagon show about 85 percent of the first 20,000 terminals in Ukraine were paid at least in part by countries such as the United States, Poland, or other entities, which also paid for about 30 percent of internet connectivity.
Deputy Pentagon Press Secretary Sabrina Singh said Friday that the US Department of Defense is in contact with Musk about the funding issue.
"We can confirm the department received correspondence from SpaceX about the funding of... their satellite communications product in Ukraine. We remain in communication with SpaceX about this and other topics," Singh said in a statement.
'Helped us survive'
She had earlier told journalists that there are potential alternatives to Starlink, but declined to provide specifics.
"There are certainly other SATCOM capabilities that exist out there. I'm not going to show our hand right now on exactly what those are or who we're talking to," Singh said, referring to satellite communications.
In overnight replies on Twitter Friday, Musk expanded on the logistics of the operation.
"In addition to terminals, we have to create, launch, maintain & replenish satellites & ground stations & pay telcos for access to Internet via gateways," he said.
"We've also had to defend against cyberattacks & jamming, which are getting harder. Burn is approaching ~$20M/month."
Musk has recently been in a spat with Ukrainian officials including President Volodymyr Zelensky after suggesting a peace deal that involved re-running controversial referendums in Russian-occupied territories in Ukraine -- an idea welcomed by Moscow.
Kyiv's ambassador to Germany, Andriy Melnyk, weighed in on Twitter, telling Musk to "fuck off."
In a Friday tweet that included the shrug emoji, Musk said: "We're just following his recommendation."
Singh declined to comment on whether Musk had decided to scrap the Starlink service in response to the ambassador's remark, saying it was a question for SpaceX.
Musk later seemed to confirm that Starlink remained operational on the frontlines, tweeting: "Starlink is only comms system still working at warfront – others all dead."
The US Agency for International Development, in a statement Friday evening, also said that "to our knowledge, SpaceX has not withdrawn service to Ukraine's civilian government agencies and critical infrastructure operators."
The Financial Times had earlier reported Starlink outages had hit Ukrainian forces on the frontline, hindering their ability to recapture Russian-controlled areas in the east of the country, but said the situation later improved.
A senior Ukrainian presidential aide, Mykhaylo Podolyak, acknowledged the importance of Starlink in a tweet on Friday.
"Like it or not, @elonmusk helped us survive the most critical moments of war," Podolyak wrote, adding that Ukraine "will find a solution to keep #Starlink working."
© Agence France-Presse