Suspect Illegal Entry Vessel X ('X' stands for unknown). Bureaucratic nomenclature that was used to denote one fateful dilapidated Indonesian fishing boat that sunk while en-route to Christmas Island on 19 October 2001. 353 people drowned, mostly Iraqi and Afghani asylum seekers who were seeking protection in Australia.

At the time the Australian government was mounting a campaign to prevent illegal immigrants from entering Australia by sea (an applicant merely needed to reach the Australian territory of Christmas Island, barely a hop, skip and jump from Java, in order to seek asylum). Two months earlier Australia, Indonesia and Norway had been at loggerheads over the Tampa Affair, when the Australian SAS boarded a Norwegian vessel that had picked up refugees and under duress sailed into Australian waters. Prime Minister John Howard received support from the Australian public for his hard line stance. In the following three weeks September 11 and the Sydney gang rapes spooked the public even more, and with an election just around the corner Howard did not want to be seen going soft.

It is believed that the vessel sank 50 miles off the Indonesian coastline in international waters. Considering the amount of maritime surveillance resources the Australian government was using in the area, questions were raised about whether anybody knew that a dangerously overloaded boat was being sent to sea. If so, why wasn't a rescue vessel sent out ? (because the rescuers would be duty-bound to accept the refugees) If not, did the ministers with the power to order rescues deliberately seek not to be advised about boats like SIEVX ?