Several NATO countries, including the US, Germany and the UK, have ruled out deploying ground troops to Ukraine, after French President Emmanuel Macron said “nothing should be excluded”.
Mr Macron said there was “no consensus” on sending Western soldiers to Ukraine.
Kremlin spokesperson Dmitry Peskov has warned of direct conflict if Nato troops deploy there.
Russian forces have recently made gains in Ukraine and Kyiv has urgently appealed for more weapons.
Mr Macron told a news conference on Monday evening: “We should not exclude that there might be a need for security that then justifies some elements of deployment.
“But I’ve told you very clearly what France maintains as its position, which is a strategic ambiguity that I stand by.”
The French leader was speaking in Paris, which is hosting a crisis meeting in support of Ukraine, attended by heads of European states, as well as the US and Canada.