RAF Tornado jets have carried out their first air strikes against so-called Islamic State in Syria, the Ministry of Defence has confirmed.
Four Tornados took off from RAF Akrotiri in Cyprus shortly after MPs voted to approve bombing.
The strikes focused on six targets in an oil field under IS control in eastern Syria, the BBC understands.
On Wednesday, MPs voted by 397 votes to 223 for UK action in Syria after a 10-hour Commons debate.
Two of the four jets have now returned to base. The Ministry of Defence confirmed they had carried out the “first offensive operation in Syria”.
BBC defence correspondent Jonathan Beale said the first pair of Tornados had left RAF Akrotiri with three 500lb Paveway bombs each, and returned to base shortly before 03:00 GMT without those weapons.
The jets used their Raptor pods – special long-range photography equipment – for surveillance, before dropping the Paveway bombs, our correspondent understands.
An RAF Reaper unmanned drone was also in the air to provide intelligence, he said.
By BBC defence correspondent Jonathan Beale, in Cyprus
The first pair of Tornados took off from RAF Akrotiri just over an hour after MPs authorised military action against Islamic State targets in Syria.
We watched the orange/blue glow from their engine afterburners disappear into the night sky. Each aircraft was carrying three 500lb Paveway bombs.
Less than an hour later, they were followed by a second pair loaded with the same weapons.
The Ministry of Defence has not given any details about their mission, but has confirmed these were the first British jets to carry out air strikes over Syria.
The use of bombs rather than the Brimstone missile suggests they were hitting static rather than moving targets – possibly infrastructure.
We waited for the first pair of Tornados to return to base. They landed after just over three hours in the air. As they taxied on the runway, it was clear to see their bombs were missing.
The relatively short mission suggests the Tornados had already been given specific targets before they left.
The Ministry of Defence is expected to give details of their targets later on Thursday.
The targeting of oil infrastructure is part of its strategy to deprive the extremists of their funding and revenue streams.
The RAF was already carrying out operations against IS – also known as Daesh – in Iraq.
Following the vote, Prime Minister David Cameron said MPs had “taken the right decision to keep the country safe” but opponents said the move was a mistake.
A total of 66 Labour MPs sided with the government as Mr Cameron secured a larger than expected Commons majority.
Welcoming the Commons result, Foreign Secretary Philip Hammond said Britain was “safer because of the actions taken by MPs today”.
He added: “Military strikes alone won’t help Syria, won’t keep us safe from Daesh. But this multi-strand approach will.”
Labour leader Jeremy Corbyn argued that the case for war “does not stack up” – but his party was split, with senior Labour figures, including members of the shadow cabinet voting with the government after they were given a free vote.
The 66 MPs who backed military action was equivalent to 29% of the parliamentary party.
Shadow foreign secretary Hilary Benn was applauded by MPs from across the House, particularly on the Conservative benches, when he urged his own side to “confront this evil” posed by Islamic State, who he said “held our democracy in contempt”.
In an impassioned speech, Mr Benn said the international community was “faced by fascists and what we know about fascists is that they must be defeated”. While there were “rarely perfect circumstances to deploy military forces”, he said “the threat is now” and the UK must rise to the challenge.