American warships in the Middle East are preparing for an escalation in fighting in case President Trump opts for a fresh round of attacks against Iran in the coming weeks, according to U.S. officials familiar with the planning.

During a rare visit to a U.S. aircraft carrier and guided-missile destroyer operating in the Arabian Sea, The Wall Street Journal observed flight operations, as well as a significant replenishment of munitions and supplies—including a large delivery of standoff land attack missiles and bunker-buster bombs designed to penetrate ground targets.