A week after an aspiring strongman launched a surprise attack on the Libyan capital, an assortment of criminal gangs and extremists are rushing into the fight against him, raising new questions for the United States and other Western powers that have condemned his attack.

A coalition of militias from around the region has stymied the assault by Gen. Khalifa Hifter, frustrating his predictions of an easy march into the capital, Tripoli, and forcing him to rely on long and circuitous supply lines through the desert to the south.

By Friday his opponents were claiming that his tanks and armored vehicles were running out of fuel.

But an increasingly unsavory cast has joined the coalition against him, including a group closely tied to a militia sanctioned as a terrorist organization by the United States and the United Nations; an extremist warlord sanctioned for undermining Libya’s stability; and other militia leaders sanctioned for migrant trafficking. That mix so alarms Western powers that some may deem General Hifter the lesser evil.

His portrayal of his fight as a battle against extremists and criminals “becomes a self-fulfilling prophecy,” argued Frederic Wehrey, a scholar at the Carnegie Endowment for International Peace.