The United States on Monday confirmed the killing of Abu al-Hassan al-Muhajir, Islamic State spokesman and a high-ranking figure within the jihadi group, in a separate U.S. operation, according to a senior State Department official.On Sunday, the Syrian Kurdish YPG militia said al-Muhajir was killed in a joint raid between Kurdish-led and U.S. forces in northern Syria.Syrian Democratic Forces (SDF) General Commander Mazloum Abdi said it was "a continuation of the previous operation" in which Islamic State leader Abu Bakr al-Baghdadi was killed over the weekend. Mazloum described the jihadist spokesman as Baghdadi's right-hand man.Muhajir was killed in the Syrian town of Jarablus in Aleppo province, said the U.S. official, speaking to reporters on condition of anonymity.The operation which led to "the demise of his (Baghdadi) No. 2, or one of his No. 2s," was also carried out by U.S. forces, the official said, adding that the SDF had a big role in it.Baghdadi, an Iraqi jihadist who rose from obscurity to declare himself "caliph" of all Muslims as the leader of Islamic State, died by detonating a suicide vest after fleeing into a dead-end tunnel as elite U.S. special operations forces closed in over the weekend, according to the U.S. government.Islamic State has no declared successor as leader. But the group has in the past proved resilient, continuing to mount or inspire attacks in the region and beyond despite losing most of its territory in recent years.