The current crisis atmosphere in U.S.-Iranian relations, in which the risk of open warfare appears greater than it has been in years, is solely, unequivocally due to the policies and actions of the Trump administration. To point this out does not mean that actions of the Iranian regime have not come to be part of the crisis atmosphere as well. It instead means that such an atmosphere would never have existed in the first place if the administration had not turned its obsession with Iran into the relentless campaign of stoking hostility and tension that has become one of the single most prominent threads of the administration's foreign policy.
Without that campaign, and without the administration's assault on the Joint Comprehensive Plan of Action (JCPOA) - the agreement that restricts Iran's nuclear program - Iran would continue to comply with its obligations under the JCPOA and all possible paths to an Iranian nuclear weapon would remain closed. The channels of communication established during negotiation of the JCPOA would continue to be available to address other issues and to defuse any incidents that threatened to escalate into war (as was done during the previous U.S. administration). Whatever Iran has been doing for years in the Middle East, such as assisting Iraq in defeating the Islamic State and assisting its longtime ally in Syria, it would continue to do. In short, there would be no new threat and no crisis.