Al-Qaeda: 'Gravest Consequences' if US Executes Tsarnaev Dzhokhar Tsarnaev was sentenced to death last year By Michael Harthorne, Newser Staff Posted Jul 1, 2016 1:03 PM CDT 112 comments Comments Al Qaeda leader Ayman al-Zawahri, seen here in 2006, warned of the "gravest consequences" if the US executes the Boston Marathon bomber. (militant photo via AP video, File) (Newser) – The leader of al-Qaeda is threatening the US with the "gravest consequences" if Boston bomber Dzhokhar Tsarnaev is executed, the Guardian reports. "If the US administration kills our brother the hero Dzhokhar Tsarnaev or any Muslim, [it] will bring America's nationals the gravest consequences," Ayman al-Zawahri says in a video posted online Friday. According to CBS News, al-Qaeda says the video was supposed to be released months ago but their copy was lost in a bombing; Zawahri apparently provided another one. Tsarnaev was sentenced to death last year, but it could be decades before his appeal of the sentence is resolved, Reuters reports. Zawahri says that if the US does execute Tsarnaev, it will "only have itself to blame" for the consequences. In the hour-long video, Zawahri also calls for more attacks against Western countries and for followers to take westerners captive to ransom in exchange for the release of Muslim prisoners. He calls Western countries "criminals" and "crusaders" who "only understand the language of force." However, Zawahri also had harsh words for ISIS, which he criticized for its "severity and injustice."