US secretary of state Antony Blinken has condemned Russia’s assault on Ukraine’s power grid, saying that Moscow had turned its war machine to such strikes in order to “turn off the heat… so that civilians suffer”.

Mr Blinken spoke at a Nato foreign ministers meeting in Bucharest, Romania, devoted in part to coordinating aid to keep the lights – and furnaces – on in Ukraine, where Russian strikes have damaged an estimated third of that country’s electrical infrastructure.

The top US diplomat said: “Because President (Vladimir) Putin is failing to defeat Ukraine militarily, he is now prosecuting war against civilians.

“And he’s doing that by trying to destroy Ukraine’s energy infrastructure, to turn off the light, to turn off the heat, to turn off the water, so that civilians suffer.”

Mr Blinken said it was “very clear” that “support remains strong, resolute, determined” on behalf of Nato foreign ministers to continue supporting Ukraine as Russia’s invasion continues.

Nato estimates that Russian strikes have damaged one-third of Ukraine’s electrical infrastructure.

It says the missiles appear to be particularly targeting vulnerable transmission networks, leaving Ukrainians dealing with darkness and cold amid freezing conditions.

Ukrainian foreign minister Dmytro Kuleba has underlined that his country’s biggest needs now are electrical gear and more advanced air-defence systems than it has gotten from the US and other allies so far, to deal with the Russian missile strikes.

“In a nutshell, Patriots and (electricity) transformers is what Ukraine needs the most,” Mr Kuleba declared on Tuesday.

Heading into a one-on-one session with Mr Blinken on the sidelines of the Nato gathering, Mr Kuleba said that Ukraine at the session had received “a number of commitments, new commitments, from various NATO members with regard to providing Ukraine with more defensive weapons and energy equipment”.

But Mr Kuleba declined to answer questions about whether that included promises of Patriot missile batteries, from the US or any other ally.

Ukraine is seeking US-made Patriot missile batteries or other more advanced air defence systems than it has gotten so far from the United States and other allies to block Russian air strikes.

Mr Kuleba did not respond to repeated questions from a reporter ahead of a meeting with Mr Blinken about whether he had gotten any commitments on Patriots.

The provision of Patriot surface-to-air missiles to Ukraine would mark a major advance in the kinds of air defence systems the West is sending to help the war-torn country defend itself from Russian aerial attack.

Nato Secretary-General Jens Stoltenberg confirmed that deliveries of such sophisticated surface-to-air missiles systems are under consideration among some allies. The military organisation does not possess any weapons – only its member countries do.

A senior US defence official said that the United States is open to providing Patriots.

While Ukraine has asked for the system for months, the US and its allies have been hesitant to provide it to avoid further provoking Russia.

German Chancellor Olaf Scholz said on Tuesday that his country’s offer to send Patriots to Poland remains on the table, despite Warsaw’s suggestion that they should go to Ukraine instead.

Ukraine does not have personnel trained to used Patriots — a complicated air defence system of which there are three main types, with varying ranges and altitudes. Germany has lent them to Slovakia and Turkey but sent its own technicians to operate the missiles.

Nato allies would almost certainly refuse to send any military personnel into Ukraine, to avoid being dragged into a wider war with nuclear-armed Russia.

They would also want guarantees that Ukraine would only use the missiles to defend its air space and not fire them into Russian territory.

Russia is deeply opposed to the move.

Dmitry Medvedev, deputy chairman of the Russian Security Council, said Tuesday on his Telegram channel: “If, as Stoltenberg hinted, Nato supplies the Kyiv fanatics with Patriot complexes along with Nato personnel, they will immediately become a legitimate target of our armed forces.”