In an audio message awaiting independent authentication, the Islamic State reportedly calls upon its members to attack a set of nations during Ramadan—an annual, month-long observance among Muslims that commemorates the first revelation of the prophet Muhammad. The message, first reported by Reuters, was distributed Monday on Telegram, an encrypted messaging app used by ISIS to disseminate videos and communicate with its followers. The voice in the audio clip seems to match that of Abi al-Hassan al-Muhajer, ISIS’s official spokesman.

In the clip, al-Muhajer lists three Middle Eastern nations—Iraq, Syria, and Iran—as potential sites for future attacks. Al-Muhajer specifically asks ISIS followers to “charge against the rejectionists and the apostates and fight them with the strength of one man.” As subscribers to a strict version of Sunni Islam, ISIS has often referred to Shiite Muslims as “apostates,” or traitors. While Sunnis make up around three-fourths of Syria’s population, Iraq and Iran are predominantly Shiite nations.

Iran was recently the site of two deadly ISIS attacks that killed 17 people and wounded dozens more. The attacks, which occurred simultaneously during the middle of Ramadan, targeted both the Iranian Parliament and the Imam Khomeini Mausoleum in Tehran. Although they represent ISIS’s first strike inside Iran, they signal the group’s mounting animosity toward the majority-Shiite nation. In Monday’s audio clip, al-Muhajer explicitly praised the recent attacks on Iran and called for additional bombings, referring to the nation as “weaker than a spider’s web.”