He accused Syria of "supporting terrorism ... pursuing weapons of mass destruction and missile programmes, including the recent revelation of illicit nuclear co-operation with North Korea".
Meddling in Iraq
The president also said Syria was "undermining US and international efforts with respect to the stabilisation and reconstruction of Iraq".
Bush initially slapped sanctions on Syria in May 2004, then extended them in April 2006 and widened them in February to target officials engaged in "public corruption," amid charges Damascus was destabilising Iraq and Lebanon.
Last month, US national security officials presented intelligence they said showed Syria had been building a secret nuclear reactor for military purposes.
They told congress the plant was being built with the help of North Korea, until its destruction by Israel in an air raid on September 6.
The International Atomic Energy Agency (IAEA) launched an investigation into the US accusations but also chided both Israel and the United States for their handling of the affair.
Syria denied the US allegations, promised full co-operation with the UN watchdog and accused the United States of a "campaign of lies" akin to US charges that Iraq had a weapons of mass destruction programme.