President Zelensky has stated that Ukraine's partners in Europe have not given him sound guarantees that they will protect his country in the event of a fresh offensive by Russia.
"I continue to pose this critical question to every one of our allies and I have not received a clear, unambiguous answer yet," he stated to the press on Wednesday.
His comments come a day after Britain and France inked a declaration of intent on deploying troops in Ukraine if a peace deal to end the war with Russia is finalized.
However, comprehensive defense assurances have not been agreed. The United States, which has been leading efforts to end the invasion, was reported to have abstained from signing such a pledge at discussions held in the French capital on the previous day.
Following the negotiations in Paris, which included some 30 countries that form the so-called Coalition of the Willing, UK Prime Minister Sir Keir Starmer said the two nations would "establish military hubs across Ukraine" to prevent any future incursion, while France's President Macron subsequently indicated thousands of troops may be deployed.
Allies proposed that the United States would take the lead in overseeing any ceasefire. But the key issue of territorial concessions that Ukraine is being pressured to offer to Russia as part of the peace proposals are still being discussed.
The Russian government has thus far remained silent on the announcement made in the city of Paris.
Russian President Vladimir Putin initiated a comprehensive military assault of Ukraine in February 2022, and Russian forces now occupies about 20% of Ukraine's land.
Sir Keir described the joint statement as "a vital part of our dedication to support Ukraine for the long-term".
He added: "It paves the way for the juridical structure under which allied military personnel could operate on Ukrainian soil, protecting Ukrainian airspace and waters, and regenerating Ukraine's armed forces for the future."
The Ukrainian leader praised that agreement as a "huge step forward".
A day later, however, he appeared less optimistic.
"I perceive the determination, the political resolve, and that the allies are prepared, and the partners are ready to give us strong sanctions, strong security guarantees," he said when questioned if nations in Europe would defend Ukraine.
"But as long as we lack such binding security pacts - formally ratified, endorsed by legislatures, supported by the United States Congress - this question remains unresolved. And should they materialize, you still have to rely primarily on your inherent capabilities."
Negotiations in Paris were also significant owing to the attendance of US President Donald Trump's peace envoys, Jared Kushner and Steve Witkoff.
Witkoff said the allies "mostly completed" their work on finalizing security arrangements.
Recently, the President indicated a peace deal was "90% ready".
Questions of land and security guarantees have been at the center of unresolved issues for diplomats.
The Russian leader has consistently stated that Ukrainian troops must pull back from the entirety of the Donbas region or Moscow will take control, rejecting any compromise over how to end the war.
Zelensky has so far ruled out ceding any territory, but has proposed that Ukraine could redeploy its forces to an agreed point - but only if Russia reciprocated the action.
Moscow now holds about three-quarters of the Donetsk region, and some 99% of the adjacent Luhansk region. The two regions constitute the industrial Donbas region.
It has been intensifying attacks against cities in Ukraine - with a focus on energy infrastructure. Moscow is also achieving incremental advances in capturing more Ukrainian territory.
Ukrainian forces have retaliated at Russian targets with unmanned aerial vehicles, though with varying degrees of effectiveness.
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