U.S. military officials say their operation against Iran is in its early stages, and more forces could head to the Middle East. Four US service members have been killed since the strikes began.
On Monday three U.S. jets were shot down by Kuwaiti air defenses in what the U.S. military called an "apparent friendly fire incident," with the crew members brought to safety.
Kate fisher reports from Washington
In: "US defense secretary"
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