"If it is confirmed that Iran tested a ballistic missile capable of delivering a nuclear weapon, Iran will have again violated both the letter and spirit of its obligations under UN Security Council Resolution 2231 (2015) not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons, including launches using such ballistic missile technology," the group wrote in a letter to President Donald Trump.   "Iranian leaders must feel sufficient pressure to cease deeply destabilizing activities, from sponsoring terrorist groups to continued testing of ballistic missiles," the letter continued. "Full enforcement of existing sanctions and the imposition of additional sanctions on Iran for its ballistic missile program are necessary. Moreover, we are hopeful that the international community can unite around the common cause of countering Iran's troubling actions."