The coalition assault on Mosul has yet to reach the city proper, but the US has already begun to prepare for what comes after the liberation of the largest urban center held by ISIS. Defense Secretary Ash Carter tells NBC News that the next major operation will target ISIS’ proclaimed capital of Raqqa in Syria, and that it will take place in “weeks.” Carter insists that the coalition has enough resources for both fights simultaneously, and that the two-pronged attack was part of the plan all along:

The offensive to oust ISIS from its capital will get underway within weeks, Defense Secretary Ash Carter told NBC News in an exclusive interview Wednesday.

“It starts in the next few weeks,” he said, referring to the timeline for an assault led by Arab and Kurdish fighters on ISIS’ Syrian stronghold of Raqqa. “That has long been our plan and we will be capable of resourcing both.”

Carter added: “It’s been long a part of our plan that the Mosul operation would kick off when it did. This was a plan that goes back many months now and that Raqqa would follow soon behind.”

Coalition forces haven’t yet entered Mosul, but they are getting closer to the city — and ISIS has begun stepping up its terrorism within it to prepare. ISIS leadership is mostly concentrated on the west side of the Tigris River, but the bulk of the city is on the eastern bank. CNN reports this morning that ISIS has sent “suicide squads” across the river, mainly comprised of foreign fighters willing to act as cannon fodder:

Witnesses said hundreds of new arrivals had streamed into Mosul from the group’s heartland of Raqqa, Syria, in the past two days, describing them as foreign fighters wearing distinct uniforms and suicide belts, and carrying light weapons.

ISIS fighters have been seen rigging bridges across the strategic Tigris river with explosives and have prepared dozens of vehicle-borne suicide bombs.

The terrorist army has begun summary executions as retribution for towns celebrating their liberation too, sending the message that the war isn’t over until it’s over. CNN also notes that they have wired bridges on the Tigris for detonation once the fight begins, which would only slow down the advance for a short period of time — presumably long enough for leadership to scatter to the west. All of these are common acts of desperation for non-state militias, but it may be difficult to credit that with ISIS, given their propensity for this kind of violence even while on the offensive.

An advance on Raqqa — real or imagined — might help in Mosul. The anti-ISIS coalition wants ISIS ejected from Iraq, but they’re not going to retreat … unless it’s to rally to a more important battle. Carter notes that the 5600 US troops in Iraq won’t take part in the “occupation” of Mosul (a poorly chosen word, considering that the Iraqis will be establishing their own legitimate sovereignty there), presumably freeing us up to assist in an assault on Raqqa. Even ISIS has to sit up and take notice of that, even if (a) the Iraqis probably won’t be ready to participate for months after liberating Mosul, and (b) might not be inclined to assist at all in Syria.

If ISIS believes that the coalition has enough resources for a siege and ground assault on ISIS’ last remaining significant city, they might be tempted to pull out of Mosul and dare the US and its allies to try. At the very least, they will have to consider limiting losses at some point and shifting them back to their “capital” rather than watch their strength bleed out hundreds of miles from where they could do some good. Even lunatic terror armies have to consider cost-benefit analyses — and that may be why they’re using up their foreign fighters first in eastern Mosul on futile suicide attacks.