Britain and France are leading efforts to create a European "security force" of around 30,000 troops to protect Ukraine after a possible ceasefire agreement with Russia.
The initiative comes as European powers fear that US President Donald Trump could end the three-year war on terms favourable to Moscow without providing security guarantees to Kiev.
The UK-France proposal is likely to focus on air and sea defence, with "minimal" forces on land and none near the eastern front line, the Guardian newspaper reported.
The Times newspaper reported that so-called US support in the form of "air support" would be essential to the plan, which would aim to deter Russia from violating any agreement.
“The area where we have a significant advantage over Russia is in the air and in our ability to respond to flagrant violations of the ceasefire,” a Western European official told the Financial Times.
It is unclear whether these considerations will satisfy Kiev or be acceptable to Moscow.
Ukrainian President Volodymyr Zelensky has previously called for a Western deterrent force of more than 100,000 personnel to help secure a lasting peace.
Russian Foreign Minister Sergei Lavrov said Russia had told the US during talks in Riyadh that it opposed any NATO member sending troops to Ukraine as part of the ceasefire.
France and the UK are two of the leading players in the military alliance.
Trump shocked Europe by saying he was ready to resume diplomacy with Russian President Vladimir Putin to end the war, turning his back on EU states and Ukraine. The US president has called Zelensky a "dictator" and blamed Kiev for starting the war several years ago.
The new US administration has expressed sympathy for some of Moscow's demands, including the detention of Ukrainians captured since 2014 and Russia's demand that Ukraine never join NATO.

Both French President Emmanuel Macron and UK Prime Minister Keir Starmer are due to visit the White House to meet with Trump next week. | BGNES