Secretary of State Marco Rubio accused Poland's foreign minister Radoslaw Sikorski of "making things up" and suggested on Sunday he was ungrateful, in a strong rebuke after Sikorski said Ukraine may need an alternative to the Starlink satellite service.

Poland pays for Kyiv to use the services of Elon Musk's Starlink, which provides crucial internet connectivity to Ukraine and its military.

Musk, a high-profile figure in the administration of U.S. President Donald Trump, said in a post on his X social media platform on Sunday that Ukraine's "entire front line would collapse if I turned it (Starlink) off."

He said he was "sickened by ... years of slaughter in a stalemate that Ukraine will inevitably lose."

The U.S. government has already revoked some access to satellite imagery for Ukraine and paused intelligence sharing, piling pressure on Kyiv as Trump seeks a swift end to the war, now in its fourth year after Russia's full-scale invasion in February 2022.

U.S. negotiators pressing Kyiv for access to Ukraine's critical minerals have raised the possibility of cutting the country's access to the service, sources familiar with the matter told Reuters in February.

"Starlinks for Ukraine are paid for by the Polish Digitization Ministry at the cost of about $50 million per year," Sikorski wrote on X later on Sunday.

"The ethics of threatening the victim of aggression apart, if SpaceX proves to be an unreliable provider we will be forced to look for other suppliers."

'Be Quiet, Small Man'

Rubio hit back at Sikorski, saying in a post on X that he was "making things up" and that "No-one has made any threats about cutting Ukraine off from Starlink."

"And say thank you because without Starlink Ukraine would have lost this war long ago and Russians would be on the border with Poland right now," Rubio added.

Musk subsequently posted on X saying Rubio's comments were "absolutely correct."

In a separate reply to Sikorski's post Musk wrote "Be quiet, small man. You pay a tiny fraction of the cost. And there is no substitute for Starlink."

A Polish foreign ministry spokesperson told Reuters by text message that providing Starlink services was not an act of charity from the U.S. and that Poland paid a subscription.

Shares in Franco-British satellite operator Eutelsat soared as much as 650% during the week ending March 7, due to speculation the company could replace Starlink in providing internet access to Ukraine.

The shares pulled back on Friday to end the week up around 380%.

Poland said in February it would continue to cover Ukraine's Starlink subscription despite sources saying the U.S. could consider cutting it.