andyt andyt:
You'll have to explain that a bit. Malaysia is Muslim as well. I doubt it Indonesia is sending suicide bombers anywhere, they're one of the most moderate Islamic states. More so than Malaysia I would have thought.
I was just tossing out possibilities. The fact that they are a moderate Muslim state is a good enough reason as any to target Malaysia, and the fact both Malaysia and Indonesia are visited by many businessmen and tourists also encourages terrorism (not tourism

). Jemaah Islamiyah is a likely suspect, being responsible for the Bali bombing in 2002, and have attempted attacks in Malaysia before (in 2008, two Jemaah Islamiyah terrorists were arrested in a plan to blow up the mall under the Petronas Towers. A plane full of infidels is as good of a target as any.
Abu Sayyaf would be another group who might be willing to carry it out, since they generally operate in the southern Philippines, and are basically scum of the highest order. Might be a bit more complex for them though, but...not impossible.
Indonesia has had tensions with Malaysia over territorial borders and maritime rights, but, I highly doubt they were involved. It's possible, but highly unlikely. Indonesia isn't Pakistan, but, some rogue operation can be theoretically possible.