WASHINGTON — A classified war simulation exercise held this month to assess the U.S. military’s capabilities to respond to an Israeli attack on Iran forecast that the strike would lead to a wider regional war, which could draw in the United States and leave hundreds of Americans dead, according to U.S. officials.
The officials said the so-called war game was not designed as a rehearsal for U.S. military action — and they emphasized that the exercise’s results were not the only possible outcome of a real-world conflict. But the game has raised fears among top U.S. planners that it may be impossible to preclude U.S. involvement in any escalating confrontation with Iran, the officials said.
In the debate among policymakers over the consequences of any possible Israeli attack, that reaction may give stronger voice to those within the White House, Pentagon, and intelligence community who have warned that a strike could prove perilous for the United States.
The results of the war game were particularly troubling to Gen. James N. Mattis, who commands all U.S. forces in the Middle East, Persian Gulf, and Southwest Asia, according to officials who either participated in the Central Command exercise or who where briefed on the results and spoke on condition of anonymity because of its classified nature. When the exercise had concluded earlier this month, according to the officials, Mattis told aides that an Israeli first strike would likely have dire consequences across the region and for U.S. forces there.
The two-week war game, called “Internal Look,” played out a narrative in which the United States found it was pulled into the conflict after Iranian missiles struck a U.S. Navy warship in the Persian Gulf, killing about 200 Americans, according to officials with knowledge of the exercise. The United States then retaliated by launching its own strikes on Iranian nuclear facilities.
The initial Israeli attack was assessed to have set back the Iranian nuclear program by roughly a year, and the subsequent U.S. strikes did not slow the Iranian nuclear program by more than an additional two years. However, other Pentagon planners have said that America’s arsenal of long-range bombers, refueling aircraft, and precision missiles could do far more damage to the Iranian nuclear program — if President Barack Obama were to decide on a full-scale retaliation.
The exercise was designed specifically to test internal military communications and coordination among battle staffs in the Pentagon; Tampa, Fla., home of the Central Command headquarters; and in the Persian Gulf in the aftermath of an Israeli strike. But the exercise was written to assess a pressing, potential, real-world situation.
In the end, the war game reinforced to military officials the unpredictable and uncontrollable nature of a strike by Israel, and a counterstrike by Iran, the officials said.