Iran flew Iranian Revolutionary Guard Corps (IRGC) commanders, military advisers and missile- and drone-related equipment into Yemen this month, according to four sources, in a move that suggests Tehran is seeking to strengthen the ability of its Houthi allies to threaten Red Sea shipping. Four sources familiar with the matter, including two Iranian sources, Yemen's information minister and a regional security analyst, said Iran transferred the IRGC personnel and military-related equipment on a flight from Tehran to Yemen on July 13, a development that has not been previously reported. The two Iranian sources told Reuters that between 10 and 21 IRGC personnel, including senior commanders, were on the Mahan Air flight. The plane was originally bound for the Houthi-controlled capital Sanaa, but diverted to the Red Sea port city of Hodeidah after the airport came under attack by the Yemeni government. "The IRGC commanders travelled there to support Houthi operations and provide training on new missile systems," one of the sources said, adding that Iran also sent gold on the aircraft to fund Houthi activities. The two Iranian sources spoke on condition of anonymity because of security concerns. The deployment offers fresh evidence of Iran's efforts to bolster the Houthis, who have been in a civil war against the internationally recognized Yemeni government for more than a decade and have attacked Gulf neighbors with missiles and drones. Iran's foreign ministry was not immediately available to comment. Tehran has repeatedly denied providing the Houthi movement in Yemen with missile capabilities. Abdel Rahman al-Ahnomi, a Houthi media official who said he was aboard the plane, described the allegations that Iran sent military experts to Yemen as "lies and fabrications", adding that all passengers aboard the plane were civilians. The Houthis have previously denied being an Iranian proxy and said they develop their own weapons.