what was the Syrian nuclear reactor and why was it destroyed by Israel?

 The Syrian nuclear reactor was a gas-cooled graphite-moderated reactor that was being built in the Deir al-Zour province of Syria, near the town of al-Kibar. 

The reactor was capable of producing plutonium for nuclear weapons and was not configured to produce electricity or conduct research. The reactor was being built with help from North Korea, and it was nearing operational capability in August 2007. 

Israel destroyed the reactor in early September 2007 before it was loaded with nuclear fuel or operated. The operation was called Operation Outside the Box and involved F-15I Ra'am fighters, F-16I Sufa fighters, one ELINT aircraft, one helicopter, and Shaldag special forces. Israel's military intelligence chief at the time, Amos Yadlin, said that even with a functioning reactor, it would have taken Syria years to build a nuclear weapon. 

Syria denied that it was building a reactor, but the International Atomic Energy Agency (IAEA) confirmed that the target was indeed the covered site of a future nuclear reactor. The IAEA also found manmade uranium particles at the reactor site, which remains a mystery.