France's Macron says Europe must be ready for war if it wants peace

French President Emmanuel Macron said on Thursday Europe should prepare for war if it wants peace, calling President Vladimir Putin's Russia an adversary that would not stop in Ukraine if it defeated Kyiv's troops in the two-year old conflict.

Macron caused controversy last month after he said he could not rule out the deployment of ground troops in Ukraine in the future, with many leaders distancing themselves from that while others, especially in eastern Europe, expressed support.

"If Russia wins this war, Europe's credibility will be reduced to zero," Macron said in a television interview.

He said it was important for Europe not to draw red lines, which would signal weakness to the Kremlin and encourage it to push on with its invasion of Ukraine. He refused to give detail on what a deployment to Ukraine might look like.

"I have reasons not to be precise," he said. "I'm not going to give (Putin) visibility."

He said France would never initiate an offensive against Russia, and that Paris was not at war with Moscow, despite the fact that Russia had launched aggressive attacks against French interests in and outside France.

"Russia is an adversary," he said, declining to call it an enemy.

Macron said Ukraine was in a "difficult" situation on the ground and that stronger support from allies was necessary.

He also said he hoped that the time would come one day to negotiate peace with a Russian president "whoever it might be", for the first envisaging the possibility of Putin no longer being in charge in Russia.