The deputy commander of the counter-Islamic State coalition is ending his tour in Iraq with a message for the several thousand terrorists still holding out against Syrian and Iraqi forces.

"Surrender or die," said British Maj. Gen. Rupert Jones, echoing a declaration made over the weekend by Iraqi Prime Minister Haider al-Abadi. "That's a pretty stark statement, but it is the truth," said Jones in a briefing to Pentagon reporters from the coalition's Baghdad headquarters.

The Iraqi prime minister was referring to the just-announced offensive to liberate Tal Afar, the last major stronghold of Islamic State in northern Iraq, but Jones says it applies equally to Raqqa, which is now about 55 to 60 percent under the control of U.S.-backed Syrian fighters.

The coalition estimates some 2,500 Islamic State forces are in Tal Afar in Iraq and another 5,000 to 10,000 in what has been dubbed the "MERV," for Middle Euphrates River Valley region.

Jones, who is wrapping up his time as the No. 2 military commander on the ground, says that Islamic State is now under tremendous pressure.

"They are losing on all fronts. They are losing on the battlefield, they are losing financially, the flow of foreign fighters has slowed to a trickle. Their narrative has been so significantly discredited," Jones said.

But most importantly, he argued the remaining beleaguered Islamic State militants are so consumed by their own survival they no longer have the wherewithal to plan or execute external attacks.

"If you are a fighter right now in Raqqa, I don't think you have the time, the bandwith, or the security to be dreaming up and plotting imaginative attacks to mount against Europe or elsewhere," Jones said. "Why? Because you are hiding on the ground and you are fighting for your life."

What remains of Islamic State frontline troops are mostly foreign fighters, who are trapped with nowhere to go and no way to get out of the region to return home, Jones said.

"The expectation has always been that we would see [Islamic State] increasingly squeezed into the middle Euphrates valley, and that is where the military defeat will be completed."