Does this indicate an imminent American attack in cooperation with Israel, or another tool to apply pressure to bring Iran back to negotiations?
Trump's ultimatum to Khamenei expires at the end of the month and the Iranians are very afraid of a military move against them.
Just as they did in Syria and Lebanon, in recent days the Iranians have begun to evacuate Iranian Revolutionary Guards from areas controlled by the Houthis in Yemen to prevent harm to them and, moreover, to avoid providing the Americans with conclusive evidence of direct Iranian involvement in the operation of the Houthis.
It is difficult to assess where Iran is headed now, and despite all the rumors online about an American attack on Iran planned for the end of May, the Iranians are capable of reversing any such decision (if it was made at all) and dragging Trump through long and exhausting negotiations until the end of his term, while at the same time fulfilling the Iranian nuclear dream (assuming it does not yet exist) and the country's military buildup.
