Around 20,000 Starlink satellite units have been donated to Ukraine since the Russian invasion in February, playing an important role in battlefield communication for Kyiv’s forces. On Friday, Musk said the operation had cost SpaceX $80 million, adding it will “exceed $100M by end of year.”

On Wednesday Ukrainian Vice Prime Minister Mykhailo Fedorov described Starlink as an “essential part of crucial infrastructure” for his country.

However, CNN has reported SpaceX wrote to the Pentagon in September, saying it would no longer be able to foot the bill for Ukraine’s Starlink access and requesting that the U.S. military take over.

In a letter the company’s director of government sales said: “We are not in a position to further donate terminals to Ukraine, or fund the existing terminals for an indefinite period of time.”

On Friday, Musk linked this decision to Ukraine’s ambassador to Germany telling him to “f**k off,” after the billionaire businessman shared a peace plan that went down badly with many Ukrainians.

Jason Jay Smart, a Kyiv Post reporter, tweeted: “Elon Musk’s Starlink says it can no longer afford to give Ukraine [Ukraine flag emoji] free service and asks the Pentagon [U.S. flag emoji] to pay for it. Starlink had been a game changer in the war.

“This comes days after Ukrainian Ambassador Andrij Melnyk told Musk to ‘f**k off.’”

In response Musk wrote: “We’re just following his recommendation,” followed by the man shrugging emoji.

SpaceX, which Musk founded in 2002, has raised more than $2 billion since June according to business information site crunchbase.

There was criticism online at SpaceX after the company said it could stop funding Ukraine’s Starlink programme, particularly after Musk linked this to Melnyk’s comment.

In response Adam Kinzinger, a Republican House of Representatives member, tweeted: “If there was ever proof that Elon Musk is playing games this is it. I’m not sure someone like this can be trusted to any longer do business with our government.”

Political consultant Adam Parkhomenko, who has 692,000 Twitter followers, accused Musk of trying to “shake down the pentagon while pretending to be a hero.”

Musk has denied reports he spoke to Vladimir Putin before presenting a peace plan, which would see Moscow keep Crimea and sovereignty referendums in other Russian-occupied parts of Ukraine.

Speaking to Newsweek, Julia Siegel, an expert in the militarization of space at the Atlantic Council’s Scowcroft Center for Strategy and Security, explained how important Starlink has been for Ukraine.

She said: “Commercial satellites are a critical enabler for military operations today, both on the physical battlefield (helping drones find and strike enemy targets) and through the information domain (allowing troops to send secure messages and exposing war atrocities to the rest of the world).

“Starlink has been a ’lifeline’ to Ukraine, a country with no national space capability, and its deactivation may hinder Kyiv’s communications capabilities.

“That said, it’s worth noting that myriad space companies exist and are active in supporting Ukraine, and keeping a vast network of commercial space partnerships could actually be a source of military advantage.”

Michael O’Hanlon, a senior fellow and director of research at the Brookings Institution think tank, agreed Starlink was important for the Ukrainian military.

Addressing Newsweek, he commented: “It’s my understanding that Starlink is the main way Ukrainian forces in the field access email and the internet and even in many cases direct voice communications networks, so it’s been quite important for intra-Ukrainian communications.”

Over the past week there have been reports of outages hitting some Starlink units used by the Ukrainian military.

Elon Musk and SpaceX have been contacted for comment.