Russia struck a bridge in Kyiv on Sunday soon after Germany's chancellor arrived in Ukraine's capital on a surprise visit to demonstrate European support in the face of an upsurge in attacks.
Air raid sirens blared across Kyiv, urging residents to shelter, soon after Friedrich Merz's arrival under tight security, with warnings of approaching Russian attack drones.
Kyiv mayor Vitali Klitschko then confirmed that a strike had damaged the road surface on the Northern Bridge -- one of several connecting the eastern and western parts of the city over the Dnipro river which have been struck in recent days.
Images posted on messaging channels appeared to show a missile slamming into the structure, sending a fireball into the air.
Klitschko has said that Kyiv -- largely spared from the devastation wrought near the frontlines in nearly five years of conflict -- should now be on a war footing due to the upsurge in attacks.
A spate of round-the-clock attacks has hit residential areas, petrol stations, schools, rail and communications infrastructure.
Merz said the country "needs all our support in the coming weeks".
"If Russia is not stopped, its war machine will sooner or later turn against us," he added.
President Volodymyr Zelensky has repeatedly urged Ukraine's Western allies for more military support, including advanced interceptors to shoot down Russia's new fast-moving, jet-powered drones.
Merz and Zelensky were due to meet and government sources in Berlin said they were expected to agree a new package of military support worth more than $1 billion.
It includes combat drones and satellite technology to help Ukraine hit Russian launch sites, as well as for the joint production of anti-jet drones, the German sources said.
"This support addresses the most significant current gap in Ukraine's air defence system. The impact is expected to be rapid and tangible," a source said.
Merz this week called for unity against Russia within NATO and the European Union as well as his own country, where the far-right, Moscow-friendly AfD opposition is on the rise.
There have been increasing fears in Europe that it could find itself in Russia's crosshairs, including from covert attacks, if it is not stopped in Ukraine.
On Saturday, Russia warned foreigners and diplomats to leave Kyiv, saying "massive" new airstrikes would hit the city.
The Russian foreign ministry declared in a statement that "responsibility for any potential negative consequences rests entirely with those who ignore this warning".
Moscow had issued a similar warning in May, but leaders from countries supporting Ukraine have defied the Russian warnings and continued to make visits.
"The EU Delegation is staying. Threatening us will not stop Europe's support for Ukraine. It only reminds us why that support matters!" EU ambassador Katarina Mathernova wrote on X on Sunday.
Mathernova told AFP separately that "nobody is moving", although European embassies always had contingency plans, including for winter, she added.
Russia has admitted deliberately targeting Ukraine's energy sector as winter approaches. Last year, similar attacks knocked out power and heating for days on end as temperatures plummeted to -20C.
In Kyiv, which is home to some three million people, residents have begun mulling what to do if that happens again. The government has also suggested that the vulnerable and disabled should consider leaving.
Merz's trip was expected to announce some 350 million euros to help provide generators, transformer stations and for grid repairs, German government sources said.