Tehran believes it should control the shipping route but its neighbour has its own plans for reopening it The strait of Hormuz is Iran’s chief bargaining tool in the negotiations with the US and so it was always likely to be the greatest point of contention. Every inch of the 24-mile-wide waterway is being contested in a test of wills and patience. For Iran, the continuation of the dispute is not a problem so long as it does not lose control.