France, Germany and Poland have promised Ukraine more military support as well as continued efforts to guarantee its future security.
The promise comes as the long-anticipated Ukrainian counter-offensive against occupying Russian forces continues.
In a show of unity, the countries' three leaders insisted they would continue to support Ukraine for as long as necessary.
“We have done everything to help it,” French President Emmanuel Macron said. “We have intensified the delivery of ammunitions, weapons and armed vehicles … We'll continue in coming days and weeks.”
German Chancellor Olaf Scholz said: “It is time that Putin finally recognises that his plan has failed, that he ends the war after almost 16 months with hundreds of thousands of dead, with millions injured and even more refugees.”
Polish President Andrzej Duda said: “I hope and believe that with our support, the counter-offensive will be successful … This victory, in my deepest feeling, will be the ousting of Russian military forces from all occupied territories.”
Ukrainian troops have retaken seven villages spanning 90 square kilometres from Russian forces in the past week, Kyiv's deputy defence minister Hanna Maliar said.
“The battles are tough, but our movement is there, and that is very important,” President Volodymyr Zelenskyy said in his nightly video address on Monday.
Despite rain and fierce fighting, Ukrainian forces were making progress on the battlefield, Mr Zelenskyy said.
“The battles are fierce, but we have movement and that is crucial. The enemy's losses are exactly what we need,” he said.
Soldiers were seen in video holding the Ukrainian flag in the village of Storozheve, along the Mokri Yaly River, which flows northward out of Russian-held territory. Reuters confirmed the location.
The three-way meeting in Paris was meant to show unity between Eastern and Western Europe, after Warsaw took on a major logistical and diplomatic role in helping Ukraine, while often castigating German and French leaders for being too slow.
Asked whether Germany agreed Ukraine needed to be given security guarantees at a Nato summit in July, Mr Scholz said: “It's clear we need this and we need it in a very concrete way.”
Mr Duda also said Nato should respond to Russia's announced intention to deploy nuclear weapons to Belarus.
“I absolutely believe that such a situation demands an unequivocal response from Nato,” he said at a joint news conference in Paris.
Russia will begin moving tactical nuclear weapons to Belarus next month, with construction of storage facilities to be completed by July 7-8, President Vladimir Putin said last week, escalating a confrontation with the US and its allies.