In 1996, Osama Bin Laden's brother in law, Mohammed Jamal Khalifa, has started funding a militant group in Yemen called "The Islamic Army Of Aden", named after the port city Aden. By mid 1998, the group starts operations and making political statements and carries about kidnappings and assaults on local law enforcement, similar to what was transpiring in the Philippines, in which Khalifa also runs small businesses and funds the Islamic militant group affiliated with Bin Laden, Abu Sayyaf. US Intelligence however, are quite familiarized with what is happening in Yemen, as the NSA and CIA have begun monitoring an Al Qaeda safehouse located in the Yemen capitol, Sana'a. The house owned by a Bin Laden associate, Ahmed al-Hada, is also sometimes frequented by the son-in-law and future 9/11 hijacker, Khalid al-Mihdhar, whom is married to his daughter.
The US monitors the house through bugs planted inside and through spy satellites to monitor people leaving and entering it. A high ranking Al Qaeda facilitator and financial courier, Walid bin Attash (Khallad), travels to Yemen and meets with Abd al-Rahim al-Nashiri as they begin preparations to attack US naval ships in the port of Aden. The plan is to attack the USS Sullivans which is part of an Al Qaeda international terrorist plot known as the "Millenium Bombing Plot", but the operation fails. On October 12, 2000 the USS Cole is bombed by martyrs from the Islamic Army Of Aden. Meanwhile, US intelligence services such as NSA had begun signals operations on Bin Laden and Al Qaeda back in 1992 or 1996 (depending on who you ask), while CIA had begun human intelligence operations in Yemen in 1996. How is it certain terrorist operations were stopped, according to them, yet certain terrorist operations were successful.
Al Qaeda In Yemen (The USS Cole Bombing Operation)