The war between the United States and Iran has demonstrated to Gulf countries just how easy it is for Tehran to shut down shipping through the Strait of Hormuz and turn the global economy upside down.

Iran has effectively imposed its own control over the vital waterway, where, prior to the war, roughly 20% of the world’s traded oil typically flowed through from Gulf countries such as Kuwait, Saudi Arabia, Bahrain, Qatar, and the United Arab Emirates. Roughly 100 to 130 ships would sail through the strait daily before the war, while there have only been around 530 vessels that have sailed through since the conflict began on Feb. 28 through May 4, the Associated Press reported, citing Lloyd’s List Intelligence.