By By Nathan Salant Jul 2, 2016 in Internet Cairo - The leader of the al-Qaida terrorist group blamed for destroying New York's World Trade Center in 2001 is again threatening the United States, this time over the fate of convicted Boston Marathon bomber Dzhokhar Tsarnaev. "If the U.S. administration kills our brother, the hero Dzhokhar Tsarnaev or any Muslim, it . . . will bring America's nationals the gravest consequences," Zawahri says on the video, according to the No specific targets were mentioned but the threat appeared to be aimed at U.S. citizens abroad. Zawahri has been leader of Tsarnaev was sentenced to death last year for planting bombs along the marathon route that killed three and gravely injured more than 200 participants in 2013 at one of the United States' oldest and most popular running race. Tsarnaev was captured in the days following the marathon attack, shortly after his brother, Tamerlan, was killed in a shootout. Zawahri urged Muslims to capture as many Westerners as possible, particularly those from countries that supported the U.S. war against terrorism that dislodged the Taliban from control of Zawahri called the U.S.-led coalition "criminals" and said "they only understand the language of force," Reuters said. The nearly one hour video included pictures of Tsarnaev but gave no indication of the location of Zawahri, who is thought to be hiding along the border between Afghanistan and Tsarnaev is awaiting execution at In a video released online, Ayman al-Zawahri warns of "the gravest consequences" if Tsarnaev or other Muslim criminals are executed."If the U.S. administration kills our brother, the hero Dzhokhar Tsarnaev or any Muslim, it . . . will bring America's nationals the gravest consequences," Zawahri says on the video, according to the Reuters news service.No specific targets were mentioned but the threat appeared to be aimed at U.S. citizens abroad.Zawahri has been leader of al-Qaida since 2011, after Osama bin Laden was killed in a U.S. raid on his compound in Pakistan.Tsarnaev was sentenced to death last year for planting bombs along the marathon route that killed three and gravely injured more than 200 participants in 2013 at one of the United States' oldest and most popular running race.Tsarnaev was captured in the days following the marathon attack, shortly after his brother, Tamerlan, was killed in a shootout.Zawahri urged Muslims to capture as many Westerners as possible, particularly those from countries that supported the U.S. war against terrorism that dislodged the Taliban from control of Afghanistan in November 2001.Zawahri called the U.S.-led coalition "criminals" and said "they only understand the language of force," Reuters said.The nearly one hour video included pictures of Tsarnaev but gave no indication of the location of Zawahri, who is thought to be hiding along the border between Afghanistan and Pakistan Tsarnaev is awaiting execution at USP Florence Admax , the high-security federal prison in Florence, Colo., while attorneys appeal his death sentence. More about alQaida, Boston, Marathon, Threats, alzawahiri More news from alQaida Boston Marathon Threats alzawahiri Ayman bin Ladan Osama