In 1999, with the violence in Northern Ireland greatly reduced due to the Good Friday Agreement, Evans moved to G-Branch, the section of MI5 which deals with international terrorism. There he became an expert on al-Qaeda and other branches of Islamic terrorism. He rose to head the section in 2001 (only a few days before the September 11, 2001 attacks), a position which put him on the service's board of management.
In 1999, after violence in Northern Ireland had significantly decreased due to the Good Friday Agreement, Evans relocated to G-Branch within MI5. This division focuses on international terrorism. He became an expert on al-Qaeda and other Islamic terrorist groups. By 2001 (just before September 11), he was appointed as the head of the section, a position that also made him part of the board of management.