Over the past several months, the brutality of the Islamic State of Iraq & al-Sham (ISIS) has become all too well-known to the outside world.

Through a series of publicly proclaimed executions and acts of cruelty, the group has made their bloodlust brazenly clear.

Yet recent events suggest that the terrorist movement ravaging the Middle East are stepping up their ruthlessness–and their strategic capacity as well.

On Sunday, the group released yet another execution video, this one showing members beheading no fewer than twenty-one captives. The individuals are all Egyptian Christians.

This most recent incident comes in the wake of the brutal immolation of Jordanian fighter pilot Moaz al-Kasasbeh, who had been shot down and captured during Jordanian airstrikes against ISIS in Syria.

Yet this mass execution stands out from earlier incidents. The footage is believed to have been taken in Libya–signalling that the organization is becoming more defiant and in a better position to take advantage of the anarchic conditions in that country.

Plus, the incident will almost undoubtedly raise the stakes for U.S. President Obama’s proposal to Congress for an Authorization to Use Military Force (AUMF) against the group. That decision is already invoking critique from Republicans and Democrats alike.

But even if the AUMF receives the green light, would it be enough to check ISIS in its tracks–let alone push it back?