Russia’s air defence systems destroyed 25 Ukrainian drones overnight over four regions, the defence ministry said on Thursday, Reuters reports.

Fourteen of the drones were destroyed over the Krasnodar region, six over the Bryansk region, three over Moscow-annexed Crimea and two over the Rostov region, it said.

Krasnodar’s regional governor, Veniamin Kondratyev, wrote on Telegram that two districts in the southern Russian region were subjected to a “massive drone attack” overnight. One civilian was injured, he said.

Explosions were heard in the Ukrainian cities of Odesa, Kropyvnytskyi, Kharkiv, Rivne and Lutsk on Thursday morning amid reports of a Russian cruise missile attack, Ukrainian news outlets Zerkalo Tyzhnya and Suspilne said.

“Energy infrastructure is once again targeted by the enemy’s massive strike,” said the Ukrainian energy minister, German Galushchenko.

The Kharkiv mayor, Ihor Terekhov, said: “The enemy continues to attack Kharkiv with missiles.

The Odesa regional governor, Oleh Kiper, urged residents to stay in shelter.

The Kyiv mayor, Vitali Klitschko, said air defence was at work.

The national power grid operator Ukrenergo had “urgently introduced emergency power cuts”, said the energy minister, German Galushchenko, as temperatures across the country dropped to around freezing.

One energy supplier, DTEK, said Ukrenergo was introducing emergency power outages in the regions of Kyiv, Odesa, Dnipro and Donetsk.

Hello, this is the Guardian’s live coverage of Russia’s war against Ukraine. This Thursday morning, Ukraine has come under widespread air raids, with a national alert issued and officials saying the country’s energy infrastructure is once again the Kremlin’s target.

More of that to come, but for now, here’s a summary from our Ukraine war briefing of other major developments:

• A senior official in Joe Biden’s administration has told the Associated Press that the US is urging Ukraine to quickly increase the size of its military by drafting more troops and lowering the conscription age to as young as 18 to help expand the pool of fighting age men available.

• The Biden administration is preparing another urgent weapons package for Ukraine, this time worth $725m, two US officials said on Wednesday. It is predicted to include landmines, drones, Stinger anti-air missiles, and Himars ammunition, including GMLRS rockets with cluster warheads. The formal notification to Congress of the weapons package could come as soon as Monday, one official said.

• Ukrainian forces made a “complex drone and missile strike” against Sevastopol in occupied Crimea on Wednesday, targeting the Belbek military airfield and a naval school, according to Russian and Crimean sources cited by the Institute for the Study of War. The attack reportedly used Ukraine’s homegrown Neptune cruise missiles, Soviet-style S200 missiles, western-provided Storm Shadow missiles, 40 strike drones and unspecified ballistic missiles. The US-based thinktank suggested it bolstered the case for the “provision of long-range strike weapons to Ukrainian forces”.

• Volodymyr Zelenskyy is due on Thursday to sign Ukraine’s 2025 budget, which calls for the country’s first wartime tax increases. The finance minister, Serhiy Marchenko, said Ukraine hoped tax increases would generate additional budget revenues of 141bn hryvnia (US$3.39bn). The prime minister, Denys Shmyhal, said record sums would be directed to weapons production and purchases including modernising Ukraine’s defence industry and buying drones.

• There was no word on whether South Korea will supply arms to Ukraine after Kyiv’s defence minister, Rustem Umerov, met with the South Korean president, Yoon Suk Yeol, in Seoul on Wednesday. Yoon’s office said the two sides agreed to continue to share information on North Korean troops in Russia and North Korean-Russian weapons and technology transfers, while closely coordinating with the US. Umerov briefed other South Korean officials on the status of the Russia-Ukraine war and expressed hope that Kyiv and Seoul would strengthen cooperation, the statement said. Umerov predicted a “tangible strengthening of security for our peoples and regions”.

• Russia’s rouble has plunged to its lowest rate against the dollar since the early weeks of the full-scale invasion of Ukraine in the wake of new western sanctions and growing geopolitical tensions, Pjotr Sauer writes.

• Donald Trump has picked Keith Kellogg to serve as special envoy for Ukraine and Russia – a newly conceived role given the ongoing war, Gloria Oladipo writes. Kellogg served as a national security adviser to the former vice-president Mike Pence, then acting security adviser to Trump himself after Michael Flynn had to resign. Kellogg has said he would emphasise getting the two countries to the negotiating table.

• Russia’s sabotage of western targets may prompt Nato to consider invoking its article 5 mutual defence clause, Bruno Kahl, head of Germany’s foreign intelligence service, has warned. The BND chief, speaking in Berlin on Wednesday, said he expected Moscow to further step up its hybrid warfare.

• Nordic and Baltic states and Poland said on Wednesday that they would in the coming months step up support for Ukraine, including to its defence industry, and invest in making more ammunition available. “We are committed to strengthening our deterrence, and defence, including resilience, against conventional as well as hybrid attacks, and to expanding sanctions against Russia as well as against those who enable Russia’s aggression,” the leaders of Denmark, Estonia, Finland, Latvia, Norway, Poland and Sweden said in a statement.

• The head of the EU executive, Ursula von der Leyen, called for more defence spending in Europe over the next five years, as her top team was voted in by a wafer-thin majority in the European parliament. The EU faces acute challenges, including the war in Ukraine, the return of Donald Trump and the climate crisis, all against a backdrop of deepening fears of economic decline as von der Leyen starts her second term.

• Poland said on Wednesday that it had detained a German citizen and charged the suspect with brokering and exporting dual-use goods to Russia. The German citizen traded in specialist machines used in the technological industry, which – through his company – were illegally sent to Russian military plants involved in the production of weapons, said the Internal Security Agency (Isa). “The suspect pleaded guilty and filed a motion for voluntary submission to punishment.”

• Vladimir Putin arrived in Kazakhstan on Wednesday. Kazakhstan is a member of the Moscow-led CSTO security alliance but has expressed concern about the Ukraine war, which the Kazakh president, Kassym-Jomart Tokayev, has refused to condone. Kazakhstan is also working to detour away from Russia as a route for its oil export, using Turkey instead.