What We're Tracking U.S.-Iran MoU set to expire. The U.S.-Iran memorandum of understanding (MoU) is set to expire on Aug. 17 with little prospect of an extension due to stalled talks. This does not necessarily portend a major shift in conflict dynamics, as both countries have repeatedly violated the MoU since it was signed on June 17. However, the expiration of the MoU may embolden Iran to strengthen some of its demands, including regarding transit fees on vessels in the Strait of Hormuz. While U.S. President Donald Trump could use the lack of diplomatic progress since the MoU took effect to justify a military escalation, his administration faces growing domestic constraints — including rising unpopularity for the war, low weapons stockpiles and poor military morale — that make prolonged economic pressure the more probable path to seek Iranian concessions.