The Singapore government announced on 16 September that it had arrested 21 men thought linked to Al-Qaeda in August; 19 belonged to Jemaah Islamiyah, which Singapore has already said planned attacks on the U.S. Embassy and an unnamed American vessel at the Changi Naval Base in late 2001, as well as a bar frequented by Americans. The other two were linked to the Moro Islamic Liberation Front, which is campaigning for an Islamic state in the southern Philippines. The men were acting on orders from an Indonesian Muslim cleric, Riduan Isamuddin (also known as Hambali). Hambali (current whereabouts are unknown) is the leader of Jemaah Islamiyah, a regional group linked to Al-Qaeda.

The U.S. Navy has a logistics unit in Singapore and warships transiting to stations off of Afghanistan have been resupplied there. American officials admitted that about 100 U.S. Navy ships pass through Singapore every year. In 2001, Singapore opened a new naval facility specially designed to accommodate U.S. aircraft carriers. 

The 21 suspects were also planning attacks on Singapore's Defense Ministry, chemical factories and Singapore's water pipelines from Malaysia. Those targets were chosen for their potential to create tensions between Singapore and neighboring Malaysia, by making the attacks appear as if they came from the Malaysians.

Singapore also arrested 13 Jemaah Islamiyah members in December 2001, claiming they planned to attack the U.S. Embassy and other Western interests. Some of the December suspects had instructed the August suspects to conduct reconnaissance and surveys of select targets in Singapore. Eighteen of the 21 Singaporeans arrested in August under Singapore's Internal Security Act will be detained for two years for their involvement in terrorism-related activities. - Adam Geibel