The war games' results have "raised fears among top American planners that it may be impossible to preclude American involvement in any escalating confrontation with Iran," the Times Mark Mazzetti and Thom Shanker wrote.

Defense experts said the reported war games results are another attempted warning signal to Israel not to go it alone or risk harming relations with the United States.

"The apparent results of the war game reported by the Times suggest that it will be much more difficult than Israeli leaders assume to keep the United States out of the conflict," former Deputy Assistant Secretary of Defense for the Middle East Colin Kahl told Yahoo News by email. "In the retaliatory spasm following an Israeli strike, the odds that Iranian actions and miscalculations could drag the United States military are substantial."

The two-week war simulation exercise--dubbed "Internal Look"--was conducted by the U.S. Central Command in Tampa, Florida. It posited a scenario in which an Israeli strike on Iran's nuclear facilities led to Iran retaliating by striking a U.S. "Navy warship in the Persian Gulf, killing about 200 Americans," thus drawing the United States into the war, the Times' report said.

"Internal Look" is designed to "refine the command's battle rhythm and assess the staff's ability to coordinate and communicate on a modern battlefield," U.S. Central Command spokesman Col. John Robinson told Yahoo News in an email Tuesday. The classified exercises took place between February 26 and March 3 at the MacDill Air Force base in Florida and at some overseas locations, he said.

But some former officials urged caution when interpreting the war games' reported results. "It's clear the administration believes an Israeli strike on Iran would be extremely problematic," Ken Pollack, a national security expert at the Brookings Institution Saban Center for Middle East studies and a former director for Persian Gulf affairs at the National Security Council, told Yahoo News in a telephone interview Tuesday. "But it is not at all clear that the game demonstrates that an Israeli strike could produce American casualties." Pollack, who has designed and directed many such war games, explained that the designers of the game could simply have created an Iranian attack on the U.S. Navy ship as a method for testing America's control system to see if it could handle it.

The report on the war games comes as Israeli Defense Forces Chief of Staff Gen. Benny Gantz is in Washington for consultations. Meantime, the State Department's lead international Iran nuclear negotiator, Undersecretary of State for Political Affairs Wendy Sherman, is in Brussels Tuesday for meetings with her international counterparts to prepare for upcoming, high-stakes talks with Iran over its nuclear program, a State Department official told Yahoo News Tuesday.