Peace talks with Russian soldiers in Ukraine could just be used by Vladimir Putin to restock his armies before launching another attack, the Foreign Secretary has warned.
In an interview with The Telegraph, James Cleverly revealed concerns that the Russian president could pretend to engage in negotiations while actually training more troops and sending more ammunition.
The Foreign Secretary said those supporting Ukraine had to be "very, very careful" when approaching the topic of peace talks, warning that Putin was not acting in "good faith".
The firm note of caution contrasts with more upbeat rhetoric from Emmanuel Macron, the French president, who this week chastised those who said Putin's departure should be a precondition of talks.
Joe Biden, the US president who has been hosting Mr Macron in Washington DC, also said he would talk to Putin if the Russian president agreed to withdraw all troops, as opposed to waiting until such an exit was complete.
In a separate development, Ursula von der Leyen, the European Commission president, risked a diplomatic spat by likening Russia's invasion of Ukraine to Britain's past rule in Ireland.
On Friday, Ukrainian officials in Kyiv said that seven of the country's European embassies had been sent "bloody parcels" of animal eyes recently in an apparent campaign of intimidation.
With the war now more than nine months old, there has been public discussion about whether there is any route to peace talks, with differences of opinion emerging among Western leaders.
Speaking to The Telegraph from a Nato summit in Bucharest earlier this week, the Foreign Secretary was asked if there could be substantive peace talks about the Ukraine war in the next year.
Mr Cleverly responded: "It's really, genuinely, it's really, really difficult to say. At the moment the atmosphere that I'm picking up here in Nato is that Vladimir Putin has not really been engaging in good faith.
"The message that I'm picking up here - and this very much echoes the message that I've been broadcasting here - is that if this isn't done right, then it isn't done.
"And the point is that we've got to be very, very careful if 'peace' talks - and I use the word 'peace' in inverted commas there - [are] initiated by Vladimir Putin."
Mr Cleverly said there was a risk "a ceasefire is actually just used by Putin to train up more troops and to produce more ammunition and to refit his damaged armed forces and to rearm his armed forces".
"Then all that will happen is we'll see exactly these scenes again, but maybe, what, I don't know, six, 12, 18 months' time."
He added: "The resolution to this needs to be sustainable, it needs to be meaningful, it needs to be real. What we have got to watch out for is a pause being utilised by Russia as just a way of making sure that its next phase of aggression is more effective than this current phase.
"And look, Vladimir Putin has got form on this. Georgia, that was going to be a one-off, wasn't it? Crimea, that was going to be a one-off, wasn't it? Eastern Ukraine, that was going to be a one-off. And actually what we saw is they were all building up towards this most latest wave of aggression."