WASHINGTON, Aug. 3 -- The weight of the naval blockade fell hardest on the ships that never chose a side. Since the United States reimposed a maritime cordon around Iran in July, 35 vessels have been redirected from their original routes, two have been disabled, and two others have been boarded, U.S. Central Command announced on Sunday. The figures mark the most detailed accounting yet of an operation that has reshaped commercial shipping in one of the world's most congested waterways.

CENTCOM's Sunday statement gave no timeline for when the redirections occurred, but the blockade itself has been in effect since July 13, when President Donald Trump ordered its reinstatement after Iran closed the Strait of Hormuz the day prior. The strait...