Tensions between Iran and the United States escalated in May 2019, with the U.S. deploying more military assets to the Persian Gulf region after receiving intelligence reports of an alleged "campaign" by Iran and its "proxies" to threaten U.S. forces and Strait of Hormuz oil shipping. American officials pointed to threats against commercial shipping and potential attacks by militias with Iranian ties on American troops in Iraq while also citing intelligence reports that included photographs of missiles on dhows and other small boats in the Persian Gulf, supposedly put there by Iranian paramilitary forces. The United States feared they could be fired at its Navy.