'We are looking for new creative and unconventional ways to pressure and punish Iran,' the CENTCOM intelligence officer wrote in the message, sent on Wednesday, according to a report. A second source said a senior officer had circulated the appeal the previous week, seeking fresh thinking on how to deal with Iran. Air power alone, the president's most senior military adviser has acknowledged, cannot accomplish everything Trump has demanded of the war. 'Air power has its limits,' the chairman of the Joint Chiefs of Staff, General Dan Caine, told lawmakers last month. That hard limit is what pushes planners towards the 'unconventional' measures the CENTCOM email requested, a category that can span cyber operations, sabotage and covert action, none of them free of risk or the danger of further escalation.