Five months into a war Donald Trump said would last only weeks, the Iran conflict has so far cost the United States tens of billions of dollars and brought about "the end of an era" in American military strategy.

Amid casualties on both sides, another energy crisis, domestic blowback, and more, how long can this be sustained?

By Idrees Ali, Patricia Zengerle and Phil StewartWASHINGTON, July 21 (Reuters) - The cost of the United States' war in Iran has risen to $37.5 billion so far, U.S. Defense…