Washington (CNN) The US blamed Iran on Tuesday for the shooting down of a US MQ-9 drone over Yemen by a surface-to-air missile, an apparent escalation of tensions between Washington and Tehran.

The US believes the missile was provided to Houthi rebels by Iran, a US official said, adding that it was not immediately clear if the drone was being operated by the US military or the intelligence community. The rebels, however, said the missile used was "developed locally" and appeared to suggest it was not provided to them by Iran.

Statements from the Trump administration and the US military, however, clearly implicated Iran in the incident, which was first reported by Reuters.

"We are aware of reports of an attack by Iranian-backed Houthi forces on a US drone. The President has been briefed and we continue to investigate the matter," National Security Council spokesman Garrett Marquis said in a statement.

"This attack is only possible because of Iran's lethal aid to the Houthis and serves as yet another example of the regime's relentless efforts to escalate conflict and threaten regional stability," he added.

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