Not allowing any meetings with the President does not mean no negotiations can take place. Groundwork can be done by diplomats, negotiators, third parties, and even high-ranking administration officials from the state department, like the Secretary of State. Such tactics can also strengthen moderates. However, a meeting with the President is a powerful symbol, and it should only take place if either significant headway has been made, or if the leaders of these regimes are fully committed to negotiating, which they can prove by agreeing to preconditions.