Ukraine is now unable to use its interceptor systems against Russian drone attacks because of a Starlink speed restriction, president Volodymyr Zelenskyy says.
He said any restrictions would have been set by the US military and US President Donald Trump.
Mr Zelenskyy told reporters in a WhatsApp media chat Ukrainian officials had been told the restrictions were linked to technical issues, adding he was discussing it with US officials.
He said Ukraine had tested Starlink on European Union territory and encountered no such problems there, with the system operating at higher speeds.
Earlier this week Ukraine experienced similar issues, with Starlink owner Elon Musk responding by insisting his firm had nothing to do with the speed limits.
Starlink is a vital battlefield communications tool and determine the speed at which some of Ukraine's weapons can travel. (Reuters)
Kyiv says Moscow carried out a 'massive' energy strike
President Zelenskyy said Moscow had carried out a massive strike on Ukraine's energy infrastructure, targeting more than 15 sites across the country.
"The sheer scale and unrelenting pace of Russia's strikes, specifically against our energy sector, are unfortunately having severe consequences," he said.
Ukraine's air force said Russian forces launched four cruise missiles and 332 attack drones overnight.
Mr Zelenskyy previously said Ukraine wasn't receiving forewarning of ballistic missile strikes from intelligence partners. (Reuters)
All of the missiles and 289 of the drones had been suppressed or destroyed, it said.
Russia's heavy bombardment of the power grid ahead of winter has been an annual feature of the war, aimed at wearing down Ukraine's appetite for the fight by denying civilians heat and running water.
Ukrainian officials have warned that Russia is stockpiling ballistic missiles for more attacks in the coming months.
Trump pauses sanctions
President Zelenskyy has also urged supporters to speak out in defence of new US sanctions against Russia, hours after Mr Trump signed an executive order pausing a sweeping package of restrictions targeting the Russian economy.
The White House decision has further raised fears Ukraine could be left exposed to Moscow's escalating assaults.
The relationship between Ukraine and the US has been strained following the announcement the US would buy diesel from Russia. (AP: Julia Demaree Nikhinson)
Mr Zelenskyy described Mr Trump's move to put sanctions on hold as unfortunate, but did not directly criticise the US leader despite deepening tensions between Ukraine and Washington in recent days.
"A decision was unfortunately made in America to completely disregard the Lindsey Graham Act, which was supposed to impose truly effective pressure on Russia to bring this war to an end," Mr Zelenskyy wrote.
He also expressed hope that the new sanctions could be revived.
"This Act could have helped enormously — and still can! But it needs to actually work, and every voice in support of it matters," he said.
Critics say Trump's decision helps Putin
Named after late South Carolina Senator Lindsey Graham, the legislation had sought to clamp down more quickly on the flow of financial resources fuelling Russia's against Ukraine.
The bill had sought to sanction Russian officials, banks and a shadow fleet of tankers that keeps Russian energy moving.
President Trump personally signed the legislation last month, two days before a deadline set in the law itself for its implementation.
The president told Congress that the pause was in the national interest but gave no further details.
Senator Richard Blumenthal, who co-drafted the bill, said in a statement Mr Trump was turning his back on "the majority of Americans, their representatives in both houses of Congress, and our European allies."
"These waivers have nothing to do with our national security, and everything to do with sucking up to Vladimir Putin,"
Mr Blumenthal said.
Mr Trump's unexpected decision comes a week after he stunningly said the US had agreed to purchase diesel from Russia to try to bring down global energy prices, despite that potentially hurting Ukraine in its war with Russia.
Mr Trump said Russia would immediately supply more than 300,000 tons of diesel, followed by an additional 500,000 tons in November and 1 million tons "immediately thereafter".
The decision has been pilloried by Republicans and Democrats alike who say it will help Russia execute its war against Ukraine — without making a difference to global fuel prices, which are elevated mostly due to Mr Trump's war on Iran.
AP/Reuters