UPDATE 1-Iran says it will respond firmly to any U.S. threat - Tasnim

Iran will respond firmly to any U.S. threat against it, the semi-official Tasnim news agency reported on Saturday, citing foreign ministry spokesman Abbas Mousavi. "We will not allow any violation against Iran's borders. Iran will firmly confront any aggression or threat by America," he told Tasnim.

The tension between Tehran and Washington has spiked since Thursday when an Iranian missile destroyed a U.S. Global Hawk surveillance drone. Tehran said the drone was shot down over its territory and Washington said it occurred in international airspace. U.S. President Donald Trump said on Friday he aborted a military strike to retaliate for Iran's downing of the unmanned U.S. drone because it could have killed 150 people, and signalled he was open to talks with Tehran. "Regardless of any decision they (U.S. officials) make, we will not allow the Islamic Republic's territory to be violated," Mousavi said.