Washington (CNN) Vice President Mike Pence on Sunday reiterated President Donald Trump's claim that there are doubts the order to shoot down a US drone by Iran was made at the highest levels.

"The President also had doubts as to whether or not the downing of our unmanned aircraft was actually authorized at the highest levels," Pence told CNN's Jake Tapper on "State of the Union."

Pence said, "We're not convinced that it was authorized at the highest levels," and told Tapper he would not speak about the intelligence the US has related to the incident.

The vice president said after Trump was provided with casualty assessments for a retaliatory strike, the President "concluded that it was not a proportionate response to shooting down an unmanned American aircraft."

Trump said Friday he called off an attack on Iran just as the US was "cocked & loaded" to strike because he decided there would be too many deaths for it to be a proportionate response to the downing of a US drone last week.

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