The Obama administration announced its intention to categorize a Syrian rebel group — with alleged ties to al-Qaeda — as a terrorist organization, as part of its effort to blunt the influence of extremists as the US steps up cooperation with the Syrian opposition.

The State Department’s action would block Jabhat al-Nusra’s assets in the US and bars Americans from doing business with the group.

The move hasn’t been announced officially, but was included in the Federal Register on Monday. Department spokesperson Victoria Nuland on Monday called the group “little more than a front for al-Qaeda in Iraq.” She assigned blame to Syrian President Bashar Assad for creating an environment that militant groups like al-Nusra could exploit.

Jabhat al-Nusra has claimed responsibility for suicide bombings on Syrian government targets, raising fears of growing Islamic extremism among the opposition.

Secretary of State Hillary Rodham Clinton is traveling to North Africa this week to try to bolster moderates hoping to end Syrian President Bashar Assad’s regime.