President Volodymyr Zelensky has said Ukraine's military is again facing "systematic" restrictions to Starlink's military-grade satellite service, Starshield, meaning Kyiv is struggling to intercept Russian jet-powered drones.
It came as US envoys Jared Kushner and Steve Witkoff met Russian President Vladimir Putin in Moscow, a day after the latest talks aimed at ending the war in Ukraine wrapped up in Abu Dhabi.
Zelensky told European leaders in Dublin that Ukraine was trying to clear up the Starlink situation with the American side.
But he added "some things" were already clear: "If someone in America is making decisions that basically treat Ukrainian territory as if it is not Ukrainian, then this tells us where things are going."
He did not elaborate further.
Starshield was developed by Elon Musk's SpaceX company for government and military use. Along with Starlink, it has come to play a vital role in facilitating communication on Ukraine's front line.
A similar issue with connectivity affected the front line in late October and lasted about a week before it was fixed. It remained unclear who had ordered the temporary restrictions on Starlink services at the time, with US officials and SpaceX offering differing explanations.
Zelensky said the current disruption had been ongoing for several days and was "helping the Russians kill more Ukrainians and carry out more accurate strikes against Ukraine".
Kushner and Witkoff are expected to travel to Dublin to meet Zelensky after their meeting with Putin.
Videos shared by Russian media on Thursday showed the US representatives disembarking a plane and being welcomed by Kremlin envoy Kirill Dmitriev with handshakes and hugs.
Later, they headed to the Kremlin where they met Putin and three of his senior advisors.
In remarks broadcast by Russian media, Putin asked the US envoys to convey his "gratitude" to US First Lady Melania Trump for her involvement in last month's Kherson region ceasefire, which allowed for the evacuation of hundreds of civilians from the Russian-occupied city of Oleshky.
The Russian president then proposed organising a similar five-day ceasefire for Kostyantynivka, a contested front-line Ukrainian city in the eastern region of Donetsk. It is unlikely that Ukraine would accept: It disputes that Russia fully holds the town, and a truce might result in Moscow's troops making a final push to seize it.
The separate in-person meetings with the Russian and Ukrainian presidents were only announced on Wednesday after two days of talks which were framed as centred around the postwar security architecture of Europe.
Nearly five years since Russia launched its full-scale invasion of Ukraine, Moscow shows no sign of backing down from its maximalist demands for sovereign Ukrainian territory and for Western countries to give up any future commitment to protecting Kyiv in case of further attacks.
On Thursday, Putin again repeated that the presence of foreign troops in Ukraine was "unacceptable" to Russia, and said Russia would like the Americans to engage with Europe "so that the Europeans can decide what they truly want: peace or war".
During the first years of the war, Europeans cut communications with the Kremlin and refused to engage with Russia directly.
However, in recent times many have grown concerned about the current US administration's commitment to European security and its softening towards the Kremlin, and have been pushing for a seat at the negotiating table.
The talks in Abu Dhabi were led by the Americans and only included Russia and Ukraine, but Kushner said he and Witkoff would ask Putin to "give his blessing" to invite European representatives in future discussions - particularly with regards to the future configuration of their continent's security architecture.
Kushner also urged Europe to "identify one person to speak on their behalf" in the negotiations.
But the Russians have been opposed to the idea, citing Europe's support for Kyiv as an obstacle.
Vladimir Medinsky, who headed the Russian delegation in Abu Dhabi, said he thought all parties had "moved closer to achieving peace" but that now "a lot depends on Ukraine, on the position of the United States, and on whether Europe comes to its senses".