Islamic State can be dealt a "decisive blow" as the international coalition targets its strongholds in Iraq and Syria, Sir Michael Fallon has said.
The Defence Secretary urged allies to keep up the momentum of attacks against the terror group as Iraqi forces prepare to launch an offensive to clear IS from west Mosul.
At a meeting of coalition defence ministers, Sir Michael said IS was also being pushed back in Syria and the mission to isolate Raqqa, the group's de facto capital, would be complete by spring, with operations to liberate it set to follow.
The RAF has been in action in Iraq in recent days, with Typhoon jets bombing an IS headquarters in north-west Mosul on Tuesday.
The Defence Secretary has also authorised UK personnel to train Iraqi forces involved in the fight against IS, also known as Daesh, at "secured and protected locations" across the country, as well as the four main sites where they had previously been based.
Sir Michael said: "Daesh is losing ground, fighters and funding. Now we need to keep up the pressure on Mosul and Raqqa to deal Daesh a decisive blow.
"Britain will continue playing its leading role providing vital intelligence, precision airstrikes and training Iraqi forces where they need it."