The delivery of weapons to Syrian rebels is in breach of UN resolutions. This enables the victims’ families to sue individually before the International Criminal Tribunal those leaders who should decide to do so, and allows Syria to file a suit against their states with the International Court of Justice.
Paulo Sérgio Pinheiro, Chairman of the United Nations International Commission of Inquiry for Syria, told the press on 21 June 2013, that “States who provide arms have a responsibility in terms of the eventual use of these arms to commit gross human rights violations, war crimes or crimes against humanity.”
The statement came on the eve of the "Friends of Syria" meeting in Doha (Qatar), in the presence of the "Free Syrian Army Chief of Staff," to discuss possible arms shipments.
For two years, members of NATO and the GCC States have been secretly supplying arms to the rebels. The "Friends of Syria" are currently discussing the possibility of doing it officially and on a larger scale.