The U.S. weighed its options as a Navy destroyer and three patrol boats continued to monitor a cargo ship flying the flag of the Marshall Islands that was seized by Iranian naval forces, officials said. The ship’s seizure appears to be illegal, according to Myron Nordquist, a maritime law specialist. Based on what’s known, “Iran had no legal basis under international law for interfering with that vessel,” which was operating in international transit lanes near Iran, said Nordquist, a senior fellow at the Center for National Security Law at the University of Virginia Sch...