French President Emmanuel Macron has said a European peacekeeping force installed in Ukraine could "respond" if Russia launched an attack.
He spoke after talks with Ukraine's president Volodymyr Zelensky and ahead of a summit in Paris of 30 nations on Thursday that will discuss the proposed force that could be set up in Ukraine if a peace deal is reached.
"If there was again a generalised aggression against Ukrainian soil, these armies would be under attack and then it's our usual framework of engagement," Mr Macron said.
"Our soldiers, when they are engaged and deployed, are there to react and respond to the decisions of the commander in chief and, if they are in a conflict situation, to respond to it."
He has been driving coalition-building efforts for a Ukraine force with UK Prime Sir Minister Keir Starmer as part of their “coalition of the willing”. It is still far from clear what kind of aid they are preparing that could contribute towards their goal of making any ceasefire with Russia lasting.
Mr Macron said the proposed European forces would not be stationed on the front lines in Ukraine, or be "engaged on the first day opposite Russian forces".
They would "be forces that dissuade the Russians from attacking again. And by holding important towns, strategic bases, mark the clear support from several European governments and allies".
"So we are not on the front lines, we don't go to fight, but we are there to guarantee a lasting peace. It's a pacifist approach," he said.
"The only ones who would, at that moment, trigger a conflict, a bellicose situation, would be the Russians if they decided again to launch an aggression."
Mr Macron is expecting 31 delegations around the table on Thursday morning at the presidential Elysee Palace - more than the number for a first meeting in Paris in February - evidence that the coalition to help Ukraine, possibly with boots on the ground, is gathering steam, according to the presidential office.
But the US will not be represented at the talks.
Donald Trump's administration has shown no public enthusiasm for the coalition's discussions about potentially sending troops into Ukraine after an eventual ceasefire to help make peace stick.
The US president's special envoy, Steve Witkoff, has dismissed the idea of a European deployment or even the need for it.
"It's a combination of a posture and a pose and a combination of also being simplistic," he said in an interview.
That is not the view in Europe. The shared premise on which the coalition is being built is that Russian President Vladimir Putin's actions in Ukraine - starting with the illegal seizure of the Crimean peninsula in 2014 and culminating in the 2022 full-scale invasion that unleashed all-out war - shows he cannot be trusted.
They believe any peace deal will need to be backed up by security guarantees for Ukraine to deter Mr Putin from launching another attempt to seize it.
Ukrainian President Volodymyr Zelenskyy and Mr Macron suggest a foreign contingent in Ukraine could also provide military training, something allies already have been doing outside Ukraine, preparing more than 75,000 troops for battle against Russia's larger and expanding military and helping to make up for some of Ukraine's losses from more than three years of intense fighting.
"Primarily, any contingent consists of combat units, but they are above all intended to control the situation, monitor it, carry out joint training, and also to prevent any desire by Russia to return with renewed waves of aggression," Mr Zelensky said at Wednesday's news conference with Mr Macron.
European officials say that under any peace deal, Ukraine's first line of defence against any future Russian aggression would be Ukraine's own army.
The 27-nation European Union is pressing ahead with a so-called steel "porcupine strategy" aimed at making Ukraine an even tougher nut for Russia to crack, by strengthening its armed forces and defence industry.
The UK is also pledging continued military aid so Ukraine can keep fighting if peace talks fail or a ceasefire is broken.
Mr Macron announced a new package of defence aid for Ukraine that he said is worth 2 billion euros (£1.6 billion) and will include light tanks, air defence and anti-tank missiles and other weaponry and support.
