The U.S. military is preparing for the possibility of sustained, weeks-long operations against Iran if President Donald Trump orders an attack, two U.S. officials told Reuters, in what could become a far more serious conflict than previously seen between the countries.

The disclosure by the officials, who spoke on condition of anonymity due to the sensitive nature of the planning, raises the stakes for the diplomacy underway between the United States and Iran.

U.S. and Iranian diplomats held talks in Oman last week in an effort to revive diplomacy over Tehran's nuclear program, after Trump amassed military forces in the region, raising fears of new military action.