The legal argument of intervention by invitation has been used by all 11 states intervening in Iraq (nine members of the US-led coalition, Russia, and Iran), by Egypt for its airstrikes against ISIL in Libya, and by Iran and Russia for their interventions in Syria. To the extent that these consensual military interventions targeted ISIL and other UN-designated terrorist groups, their legality has not been challenged by any state. Strong criticisms marked nonetheless military operations undertaken by invitation, but not targeting ‘terrorist groups’, such as the alleged Russian strikes against the ‘Syrian moderate opposition’. The arguments advanced by intervening states seem to confirm the purpose-based approach of intervention by invitation. They did not claim a ‘right to intervene in a civil war’, but relied on the existence of both a request by the government and a legitimate purpose: fighting ISIL and other terrorist groups. The different reactions also show unwillingness by the international community to recognize a general right of intervention in a civil war. Turning to the strikes of the US-led coalition in Syria, it is impossible to rely on the legal basis of ‘intervention by invitation’. The controversial theory of ‘passive consent’ could be used to some extent – but not after September 2015 when Syria denounced these strikes as a ‘flagrant violation’ of its sovereignty. The current efforts of the international community to find consensual solutions to the dramatic conflicts in Syria, Libya, and Iraq could offer new possibilities of consensual interventions against ISIL and other terrorist groups.