Ukrainian President Volodymyr Zelenskyy signed an “ambitious and substantive” long-term security pact with France on Friday after securing a similar deal and aid from Germany.
The trip comes as western officials expressed concerns that the Ukrainian military is running low on ammunition in its fight against Russia.
The 10-year security pact with France includes commitments by Paris to deliver more arms, train soldiers and send up to €3 billion ($3.2 billion) in military aid to Ukraine in 2024.
“It's an ambitious, very substantive security agreement,” Mr Zelenskyy told reporters alongside French President Emmanuel Macron.
“This is not an alternative to the United States. We are all together and this union is necessary to defeat Russia.”
Mr Macron told a joint news conference that France's “commitment to Ukraine will not weaken” and added that the “Kremlin regime” had entered a new phase that was now clearly showing more aggression towards European countries.
Advisers to Mr Macron said that the agreements come in the wake of the establishment of a framework for bilateral support to Ukraine by Nato allies in July.
The German security pact, which will last for 10 years, commits Berlin to supporting Ukraine with military assistance and hitting Russia with sanctions and export controls, and ensuring that Russian assets remain frozen.
Berlin has also prepared another immediate support package worth €1.13 billion that is focused on air defence and artillery.
“The document's importance cannot be overestimated. It makes clear that Germany will continue to support an independent Ukraine in its defence against the Russian invasion,” Germany's Chancellor Olaf Scholz said.
“And if in the future there is another Russian aggression, we have agreed detailed diplomatic, economic and military support.”
The UK was the first country to deliver on the pledge when Prime Minister Rishi Sunak signed a security agreement with Ukraine on January 12.
The Paris agreement included “economic support and civil assistance to strengthen economic stability and Ukraine's resilience”, one of the advisers said.
The adviser said that Nato allies had chosen to specialise in different types of military aid to Ukraine.
“We took the lead in artillery and air defence. The UK took the lead in other topics including maritime issues and drones.”
France has supplied Ukraine with Caesar self-propelled howitzers, Crotale surface-to-air missiles and Scalp cruise missiles.
There have been reports of a widening rift between Paris and Berlin over military support to Ukraine, with France touting quality over quantity provided by Germany.
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Putting figures on military support may indicate the “financial accumulation of aid provided” to Ukraine, but it is “also important to note the qualitative aspect … of what is delivered”, an adviser to Mr Macron said.
France is not “in a beauty contest” with Germany, the adviser added.
“Support cannot be reduced to numbers.”
A second adviser said that discussing such matters played into Russian President Vladimir Putin's hands.
“Russia wants to see European cohesion around Ukraine to crack,” the adviser said. “We do not want to fuel this debate.”
Mr Zelenskyy's trip comes after leaders of the EU's 27 members sealed a deal earlier this month to provide Ukraine with €50 billion ($54 billion) in support for its battered economy.
Yet western officials also worry about Ukrainian commanders reporting that they are running out of ammunition on the front line as the European defence industry struggles to meet their demands.
“We are very much committed to giving the ammunition that Ukraine needs and providing them with that but we are struggling, of course, on the side of our production capacity,” Dutch Defence Minister Kajsa Ollongren said on Thursday at a meeting of Nato defence ministers.
Western leaders have also urged the US to approve a huge aid package to Ukraine which has been bogged down by partisan politics.
“I expect the US to be able to make a decision, that Congress and the House of Representatives will agree continued support to Ukraine,” Nato Secretary General Jens Stoltenberg said.
