Militants from so-called Islamic State in the group's final area of territory "have sworn to fight to the very, very bitter end", according to the officer in charge of the UK's air campaign.
IS, also known as Daesh, are centred in their only remaining Syrian enclave of Baghouz, a town in eastern Syria.
Air Component Commander, Air Commodore Justin Reuter, says the militants occupy an area of around two kilometres which is surrounded by cliffs, the Euphrates river, and troops of the Syrian Democratic Forces (SDF), who are looking to recapture the last IS enclave.
The RAF officer says the battle will be fraught with difficulty.
"It will look very much like a camp but there are tunnels in there," says Air Cdre Reuter.
"There are Daesh fighters mixed in with their families. Women and children. Non-combatants and combatants in a very small area."
Air Cdre Reuter also warned the Syrian troops will face IS fighters that are prepared to fight to the death.
"Some of these fighters are equipped with suicide vests," Air Cdre Reuter said.
"With vehicle-borne IEDs (improvised explosive devices) and some of them have sworn to fight to the very, very bitter end".
With the Tornado now retired, the Typhoon is leading the UK’s air campaign on IS, called Operation Shader.
Six are based at RAF Akrotiri in Cyprus, with four of them flying missions on most days.
The air operation has been underway for more than four years.
Air Cdre Reuter suggested air strikes against IS fighters in the enclave will be difficult as the area will contain families, prisoners and civilians.
"We know that Daesh have captured not just SDF but also tribesmen who live in that area as well and taken them hostage."