German Chancellor Friedrich Merz has warned that Russian President Vladimir Putin's "imperialist plan wouldn't end with the conquest of Ukraine but would rather be just the start".
Speaking at a conference of Germany's ambassadors, Mr Merz said "we are experiencing daily and with increasing intensity hybrid Russian attacks, including on our infrastructure" and pointed to Moscow's "provocations in the North and Baltic Seas".
Germany has been Ukraine's second-biggest supplier of military aid since Russia's invasion began in 2022 and has been on high alert for sabotage plots directed from Moscow.
Mr Merz has moved to ramp up Germany's defence capacities in the face of US President Donald Trump's questioning of the future strength of the transatlantic alliance and wants Germany to have Europe's "strongest conventional army".
"We have historic tasks," Mr Merz said today, namely "building a new security architecture which should last for several decades to come".
"What we referred to as the liberal world order is under pressure from many sides, including within the political West," he said.
"A new conflict between systems has broken out between liberal democracies and an axis of autocracies."
EU leaders to meet President Trump
The comments come as US President Donald Trump said individual European leaders will visit the United States today or tomorrow to discuss how to resolve the Russia-Ukraine war.
Speaking to reporters after returning from the US Open in New York City, Mr Trump also said he would speak to Russian President Vladimir Putin soon.
"Certain European leaders are coming over to our country on Monday or Tuesday individually," he said.
It was not clear to whom the US president was referring and the White House did not immediately respond to a request for further details.
Mr Trump added that he was "not happy" about the status of the Russia-Ukraine war after reporters asked about a massive Russian air assault yesterday that Ukrainian officials said had set the main government building in Kyiv on fire.
But he again expressed confidence that the war would soon be settled.
"The Russia-Ukraine situation, we're going to get it done," Mr Trump said.
Watch: Trump says European leaders to visit US
His remarks come after Ukrainian officials said Russia launched its largest air attack of the war on the country.
Ukrainian President Volodymyr Zelensky said the drone and missile barrage killed four people and caused damage across the north, south and east of the country, including the cities of Zaporizhzhia, Kryvyi Rih and Odesa, as well as in the Sumy and Chernihiv regions.
The Ukrainian president said he is counting on a strong US response to the Russian barrage.
"It is important that there is a broad response from partners to this attack," Mr Zelensky said in his evening address.
"We are counting on a strong response from America. That is what is needed," he added.
Residential apartments were hit and damaged in Kyiv, with dozens of residents wrapped in blankets gathering on the streets outside to survey the damage to their homes as rescue workers fought to extinguish the flames.
The attack underlined growing pessimism in Ukraine and among allies that the war can be ended any time soon, with Mr Putin resisting calls for a ceasefire and emboldened by strengthening relations with China.
Mr Trump had earlier said he is ready to move to a second phase of sanctioning Russia, the closest he has come to suggesting he is on the verge of ramping up sanctions against Moscow or its oil buyers over the war in Ukraine.
He did not elaborate.
Until the comment, Mr Trump, who met Mr Putin last month, has resisted imposing tougher sanctions on Russia.
US Envoy to Ukraine Keith Kellogg said the Russian attack looks like an escalation in the conflict.
"The attack was not a signal that Russia wants to diplomatically end this war," Mr Kellogg wrote on X.
US Treasury Secretary Scott Bessent said additional economic pressure by the United States and Europe could prompt Mr Putin to enter peace talks with Ukraine.
Kyiv's European allies have condemned the attack and vowed to stand by Ukraine politically and militarily, but concrete offers of assistance, including the possibility of troops on the ground, are still being discussed.
