US State Department spokesman Matthew Miller. (Source: PTI)

At a press conference on September 26, US State Department spokesman Matthew Miller said: “Iran must take steps to de-escalate if it wants to reduce tensions and create space for diplomacy.

“In just the last few weeks, we have seen Iran taking steps to undermine the IAEA’s ability to do its job. So if Iran is serious about taking steps to de-escalate, the first thing they can do is cooperate with the IAEA.”

The steps are seen as a potential prelude to resuming US-Iranian talks, whether directly or indirectly related to Tehran’s nuclear program, Miller said, without providing further details.

This is the second time in recent days that Washington has condemned Tehran for its decision to ban many IAEA inspectors from being assigned to the mission, hampering the work of the UN nuclear watchdog on Iran's atomic issue.

The US and many Western allies are concerned that Tehran's nuclear program could be a cover for developing nuclear weapons, but Iran has always denied these allegations.