The missile missed the drone and fell into the water, the official said.
Prior to taking fire, the American MQ-9 drone observed Iranian vessels closing in on the tankers, the official added, though the source did not say whether the unmanned aircraft saw the boats conducting an actual attack.
Still, it is the first claim that the US has information of Iranian movements prior to the attack.
The same official also said in the days prior to the attack, a US reaper drone was shot down in the Red Sea by what is believed to be an Iranian missile fired by Houthi rebels.
The Pentagon had tough words for Iran on Friday as the US continues to assert its claim that Tehran was responsible for the attack on the two oil tankers in international waters after releasing video footage its says shows an Iranian patrol boat removing an unexploded mine from one of the vessels’ hulls.
“We’re making sure that General McKenzie and the central command has the resources and the support that they need to conduct their missions,” acting Defense Secretary Patrick Shanahan said, adding that the US continues to work on building an international consensus that Iran was behind the attack.
The United Kingdom released a statement Friday saying it is “almost certain” that a branch of the Iranian military — the Islamic Revolutionary Guard Corps (IRGC) — attacked two tankers.
The IRGC is an elite wing of the Iranian military that was established in the aftermath of the country’s revolution in 1979. In April 2019, the US officially designated it as a foreign terrorist organization, a move which was rejected by authorities in Tehran.
No other state or non-state actor “could plausibly have been responsible,” the statement added.
But Iran does not appear to be backing off and continues to engage in provocative behavior, according to a US official who told CNN on Friday that Iranian small boats are preventing tug boats from towing away one of the damaged tankers.
President Donald Trump seems convinced that Tehran was responsible.
“Iran did do it and you know they did it because you saw the boat,” he said, appearing to refer to the images and video released by the Pentagon late Thursday.