On 30 September 2015, Russia started formal military intervention in the Syrian Civil War.[57] It has consisted of air strikes by Russia against militant groups opposed to the Syrian government, including al-Nusra Front, the Islamic State and the Army of Conquest.[58][59][60] The Russian Air Force had significant ground support from the Syrian military, Iranian Revolutionary Guards, and allied militias.[61] Prior to this intervention, Russian involvement in the Syrian Civil War had mainly consisted of supplying the Syrian Army.[62] Russia intervened after a formal request from the Syrian government for military help against rebel and jihadist groups in Syria.[63] Russian officials have acknowledged their objective is to help the Syrian government retake territory, including from opposition fighters backed by the United States. The intervention could last a year or more, according to reports.[64]