Though U.S.-trained forces dominated by Iraqi Shiites have been accused of committing war crimes as they advance on ISIS-held territory in and around the city of Tikrit, the majority of that city and nearly all of its outskirts have fallen to pro-Baghdad forces. As of yesterday, only an estimated 150 ISIS fighters continued to hold out inside the final quarter of the city they continue to control.

Elsewhere in Iraq, however, the fight against ISIS has not yielded results so favorable to the West. In Ramadi, the capital city in the restive Sunni-dominated Anbar province, 40 Iraqi soldiers were killed on Friday when Islamic State militants attacked a military headquarters.

“Ramadi has been the focus of a fierce ISIS assault since Wednesday, launched at the same time as Iraqi forces made gains against the Sunni extremist group in an offensive in Tikrit, about 100 miles to the north,” a CNN report read.

But ISIS does not necessarily need to conquer territory in order to expand the reach of its nascent caliphate. The militant Islamist group is reportedly expanding its influence via alliances with other aspiring Islamist militant groups that are busily acquiring territory across North Africa and the Middle East. On Thursday, reports indicated that ISIS leadership had agreed to a proposed alliance with the equally brutal Nigerian Islamic militant group Boko Haram

“Islamic State (IS) has accepted a pledge of allegiance from Nigeria’s militant group Boko Haram, according to an audio message,” the BBC reported.

In the tape, a man – who describes himself as IS spokesman Mohammed al-Adnani – says: “We announce to you to the good news of the expansion of the caliphate to West Africa because the caliph… has accepted the allegiance of our brothers of the Sunni group for preaching and the jihad.”

The spokesman also urges Muslims to join militants in West Africa, rejecting suggestions that Iraqi forces and the US-led coalition have recently had a series of victories against IS in Iraq and Syria.

That audio has since been verified by the global security firm and NBC News consulting group Flashpoint Intelligence.

This alliance represents a significant diplomatic victory for the Islamic State. Pockets of territory from the heart of Nigeria, to the Mediterranean coast of North Africa, to the outskirts of Baghdad are now controlled by loosely affiliated Islamic militants. The operational range of these militant groups stretches from the Niger Delta to the border of NATO-allied Turkey.

For now, the geopolitical and logistical implications of an informal alliance between Boko Haram and ISIS are limited. It is nevertheless disturbing to see the influence of the Islamic State increasing even after eight months of America-led coalition airstrikes on ISIS targets in both Iraq and Syria.