India, Feb. 28 -- The United States has begun what President Donald Trump described as "major combat operations" in Iran, escalating tensions in the Middle East and prompting urgent questions over how Tehran might respond.

Trump announced the launch of the military campaign in a video message, vowing to eliminate any nuclear threat posed by Iran.

Israeli officials confirmed strikes on Iranian targets, while Iranian state media reported explosions in central Tehran, with plumes of smoke seen rising over the capital.

Iran has warned it would retaliate if attacked. NBC News reported that Tehran said any strike would trigger attacks on American and Israeli bases in the region, warning of a "devastating war."

Israel declared a state of eme...