US and Russian officials on Oct. 20 signed a memorandum of understanding aimed at preventing any mid-air conflicts over Syria, the Defense Department announced. The agreement, which has been in the works for weeks and included multiple secure teleconferences between defense officials from both countries, establishes protocols for “maintaining professional airmanship at all times,” along with establishing specific radio frequencies for aircrews to use, and creating a ground-based “line of communication” to use as a backup if crews have issues with contact mid-flight, Pentagon spokesman Peter Cook said Tuesday. The Pentagon will not release specifics of the agreement, at Moscow’s request, Cook said. The most detail the Defense Department could disclose is that the agreement creates a “series of protocols in place that effectively are intended to avoid any sort of risk of a mid-air incident,” Cook said. The agreement comes after multiple incidents where Russian aircraft flew close to US manned and unmanned aircraft over Syria, and will cover both US and coalition aircraft. The US has no desire to have a similar agreement with either Iran or Syria, Cook said.