(CNN) — President Donald Trump said the US must respond after Iran brought down an Army Apache helicopter, whose crew members were safely rescued. Trump posted on social media Tuesday afternoon that the US military informed him Iran shot down the helicopter, which was patrolling the Strait of Hormuz, off the coast of Oman. “There were two pilots involved, both are safe and uninjured. Nevertheless, the United States must, of necessity, respond to this attack,” he said.