German Chancellor Friedrich Merz and Ukrainian President Volodymyr Zelenskyy accused Russia of stalling diplomatic efforts to achieve a cease-fire at a joint news conference in Berlin on May 28.
The two leaders also announced that their countries would begin joint production of long-range weapons to boost Ukraine's ability to fight.
"They (Russians) will constantly look for reasons not to end the war," Zelenskyy said, adding "you can see what [Russian President Vladimir] Putin is doing."
"There are mass drone attacks every night. The Russians use dozens of cruise missiles, ballistic missiles, hundreds of drones," he added.
"The memorandum on talks, which Putin promised more than a week ago, has still not materialized. The massive air strikes, especially on Kyiv at the weekend, are not the language of peace," said Merz.
"They are a slap in the face for everyone who is working for peace, in Ukraine, in Europe, and in the United States," he added.
Their comments came added to a growing sense on both sides of the Atlantic that efforts to get negotiations moving are being blocked in Moscow.
They follow a social media post by US President Donald Trump the previous day, warning that Putin was "playing with fire."
"What Vladimir Putin doesn't realize is that if it weren't for me, lots of really bad things would have already happened to Russia," he wrote.
Trump's post followed a weekend in which Russia launched its largest air attack since beginning its full-scale invasion in 2022.
Zelenskyy said that more than 900 missiles were fired at Ukrainian targets over a three-day period ending early on May 26. Thirteen civilians were killed in the attacks that took place on May 25.
Moscow has insisted it only hits military targets in Ukraine, despite ample examples where it has hit housing, energy infrastructure, schools, hospitals, restaurants, and other civilian areas.
Ukraine has launched drone and some missile strikes on Russian territory but on a much smaller scale. Its ability to hit back at Russia was a big issue ahead of this visit, with much speculation about whether Germany would supply it with Taurus cruise missiles.
Instead, Merz announced the joint production of long-range weapons.
"Our defense ministers will today sign a letter of intent on the creation of long-range weapons systems, produced by Ukraine," he said.
"There will be no range restrictions. This will enable Ukraine to fully defend itself, even against military targets outside its own territory. This marks the beginning of a new form of military-industrial cooperation between our countries."
Merz added that this would result in joint production but would not be drawn on details such as where this would take place.
Zelenskyy welcomed the deal but also said Ukraine was still interested in Taurus missiles. "Of course we need them, of course we will discuss this issue," he said.
Kremlin spokesman Dmitry Peskov issued a scathing response to the joint production plan.
"In this particular case, we see Germany competing with France for
leadership in further provoking war," he said.
"All these actions are certainly obstructing peace efforts. We hope that, despite provocative actions and all obstacles, we'll be able to continue the settlement process," he added.
