The president, citing his authority under the Arms Export Control Act, and announced that he would "waive the prohibitions in sections 40 and 40A of the AECA related to such a transaction."
Those two sections prohibit sending weaponry to countries described in section 40(d): "The prohibitions contained in this section apply with respect to a country if the Secretary of State determines that the government of that country has repeatedly provided support for acts of international terrorism,"
Why would he need to waive a Federal Law , such as this, which clearly relates to not providing arms to terrorists, unless he knew by not doing so, he'd be guilty of breaking a Federal law by giving suspected Terrorists arms. If they aren't Terrorists, he would not need to waive this law.