Why is Syria being considered a threat to the US?

I am just confused about this issue... Isn't Syria a predominantly Christian country? (just want to clarify that it isn't about Muslim jihadists ;) ) I know there is a territory problem between Israel and Syria - is it simply because Israel is a US ally? And what about the bombing of a supposed nuclear reactor facility built in Syria with the help of N. Korea? Seems strange that N. Korea, Iran and Syria would be in bed together, but I guess I am missing something - according to these articles. What are your opinions?