Ukraine's President Volodymyr Zelenskiy and German Chancellor Olaf Scholz visit an exhibition of Ukrainian unmanned vehicles, amid Russia's attack on Ukraine, in Kyiv, Ukraine on Monday. (Reuters)

German Chancellor Olaf Scholz unveiled 650 million euros ($685 million) of new military aid as he came to Kyiv on Monday, vowing Berlin would remain Ukraine's biggest backer in Europe at a crucial moment in the war, with Donald Trump set to return to the White House.

The visit, his first to Kyiv since the early months of Russia's invasion in 2022, comes weeks after his governing coalition collapsed, setting him up for a tough election battle in February.

The political turmoil in Europe's biggest economy adds to a growing feeling of uncertainty in Ukraine, with Russian troops advancing ever faster. It is unclear how much Kyiv's European allies can step up support for Ukraine if Trump cuts back help from its biggest backer.

Scholz and President Volodymyr Zelenskiy met at an undisclosed location and reviewed military drones manufactured by Ukrainian and German firms. They also visited a hospital and spoke to people wounded in the war.

Scholz was expected to hold talks later with Zelenskiy, whose government is urging NATO to invite Ukraine to join the military alliance at a meeting in Brussels this week.

While trumpeting Germany as Ukraine's second-biggest weapons supplier after the United States, Scholz has repeatedly refused to send Taurus cruise missiles to Ukraine, fearing this could draw his country into a direct conflict with Russia.

He also drew fire from allies, including Zelenskiy himself, for holding a phone call with Russian President Vladimir Putin in November, for the first time in almost two years, which critics saw as a bid for domestic political gain.

"Germany will remain Ukraine's strongest supporter in Europe," Scholz wrote on X, adding that he would promise Zelenskiy "further military equipment worth 650 million euros," to be delivered this month.

The package includes IRIS-T air defence systems, Leopard 1 tanks and armed drones, a defence ministry spokesperson said.

On Sunday, new European Council president Antonio Costa and new EU foreign policy chief Kaja Kallas visited Kyiv on their first day in office to demonstrate the EU's support.

Ukraine an issue in German election campaign

Backing for Ukraine is shaping up as a major issue in Germany's election.

Friedrich Merz, the conservative opposition leader who is on course to unseat Scholz, has said Germany should send Taurus missiles and at the weekend said Scholz was raising unnecessary fears.

Roderich Kiesewetter from the conservative Christian Democrats accused Scholz of "campaigning on the backs of the Ukrainian population and at the same time ... feeding the Russian fear narrative."

"He is increasingly isolating Germany and endangering our security," he told Monday's Augsburger Allgemeine newspaper.

Moscow's troops have been capturing village after village in Ukraine's east, pushing to fully seize the industrial Donbas region, while Russian airstrikes continue to target a hobbled Ukrainian energy grid as winter sets in.

In November, the outgoing Biden administration granted Ukraine permission to use Western missiles to strike further into Russian territory. Moscow responded by attacking Ukraine with a new intermediate-range ballistic missile, and has threatened strikes on government sites in Kyiv.

Kyiv has long demanded Moscow withdraw all troops from its territory. It also wants Western security guarantees comparable to NATO membership to prevent Russia attacking again.

Moscow, which controls nearly a fifth of Ukrainian territory, demands recognition of its annexation of Ukrainian land and permanent neutrality for Ukraine.

Last week Zelenskiy floated the idea of Ukraine being granted NATO membership even while Russia occupies some captured territory, which he said could end the "hot stage" of the war.

On Sunday, he clarified that any invitation to join NATO must extend to all Ukrainian territory, even if the alliance's collective defence agreement might not operate in areas occupied by Russian forces. (Reuters)