Al-Qaeda leader Ayman al-Zawahri has issued a statement urging all Sunnis worldwide to flock to Syria to join the civil war, saying it is vital that they “spare no effort” to ensure that not only is Assad ousted, but that US-backed secular rebels don’t replace him.

Zawahri’s statement came by way of an audio recording posted on a militant website. It wasn’t clear exactly when the record was made, but it urged Sunnis to “rise above their differences” and focus on defeating the Shi’ites.

The comments admonishing them to fight other, different rebels appears to mirror similar efforts by the US to get secular rebels to abandon the fight for regime change, at least in the near-term, and focus on fighting the Islamist rebels.

The big difference is that the Islamist rebels seem to have a considerable advantage on the ground, at least compared to the relatively small secular rebel forces, which have appeared more or less rudderless over the past several months. The US has repeatedly expressed annoyance with the lack of leadership among secular fighters, and efforts to back them at the expense of the Islamists has not borne any fruit.