Ukraine is still recording issues with the Starlink internet network, sources within the defence ministry say, after Donald Trump said limits had been reversed by Elon Musk who owns the satellite system.
The sources told the BBC that instances of drones experiencing connection loss at speeds of 161km/h (100mph) were being recorded, hampering military operations.
The US president had denied instructing the tech billionaire to restrict connectivity to Starlink's military-grade counterpart, Starshield, before saying on Thursday that Musk had "put it back".
Asked on Friday, Trump said: "If there is a problem, I will get it straightened out."
Trump added: "I have not spoken to him. I might have to, but I have not. I've heard it was fixed, but if it's not, I'll speak to him."
Musk previously said he was not behind the slowdown, which affected Ukraine's ability to use attack drones and co-ordinate defensive operations.
Trump told reporters he did not think the tech billionaire had too much power.
The Ukrainian defence ministry sources said the military was constantly monitoring the performance of both the Starlink and Starshield networks.
They added that there was "currently no confirmation that these restrictions have been lifted".
Last week, Kyiv said uplink speeds to the low Earth orbit satellites had been restricted, affecting the speed at which drones could travel. Any drone travelling faster than 100mph lost its connection, officials said.
Shortly after, Musk said that Starshield, which Ukraine uses for some of its operation, was controlled by the US military and suggested that the Pentagon could be behind the issues.
The White House has since repeatedly denied deliberately placing limits on the network in Ukraine.
In a call with Trump on Friday evening, British Prime Minister Andy Burnham "underlined the importance for Ukraine to have full access to Starlink so they can continue to defend themselves against Russia's full-scale invasion", Downing Street said in a statement.
Ukraine uses both the civilian service Starlink and the more secure Starshield, depending on what communications are needed.
The networks use 10,000 satellites to provide connectivity, particularly in remote areas and on the battlefield. Starshield allows Ukrainian drone operators to see targets in real time, as well as operate interceptor drones.
Russia is not authorised to use Starlink, so when Ukraine sends long-range missiles deep into Russia to hit oil refineries, the network does not work.
One Ukrainian soldier said there was "simply no alternative" to Starshield, adding that earlier in the week, connectivity had been cutting out when his unit had been travelling in a car at 80km/h (50 mph).
"I'll tell you this much: God forbid they shut it off completely - it would be an absolute catastrophe," he told the BBC. "We need a backup option for securing communications and internet."
Another soldier said they had reverted to the "proven algorithms" they used before they had Starlink when it initially started playing up, but stressed that Ukrainian forces did need the network, citing its speed.
"Even one or two seconds is critical when we can transfer data and orders faster," she said. "You can really feel that advantage on the battlefield."
Ukrainian reports of a slowdown to the service came during a tense diplomatic row between Trump and Ukrainian President Volodymyr Zelensky about Ukrainian strikes on Russian oil infrastructure.
Faced with midterm elections next month, Trump has waived some sanctions on Russia and agreed a deal to import Russian diesel for the US market - a move criticised by Ukraine and its European allies.
Trump said the strikes on Russian oil refineries, which Kyiv says are crucial to stemming the main revenue source for Moscow's war effort, have pushed global prices higher.
While the attacks have had an impact on global fuel prices, rises seen this year have primarily been due to the Iran war.
Zelensky said the US had also threatened to withdraw intelligence sharing if the strikes did not stop, something Trump later denied.
The row prompted a war of words between the two world leaders, with Trump suggesting it was time for Ukraine to get a new president and Zelensky implying Trump was not a real leader.
Earlier on Thursday - before Trump's comments - Zelensky had said the speed of the system had still not been restored fully.
"I am waiting to hear from US Secretary of State [Marco] Rubio. He promised to get back to me with information within 48 hours or so."
The Wall Street Journal reported that Trump had told Musk that he was frustrated the Starlink system's speeds were still capped, and that the system was working closer to normal following that conversation.
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