There was also the 7/7 London bombings. To head bin Laden tell it, the Bali bombings were a mix of retaliation for the US attacking Afghanistan and being generally evil, but also Australia's role in East Timor.

There's no question real threats exist. But the most effective way to stop them (in countries with due process and law enforcement) is old fashioned intel and police-style work. And even that won't be 100% effective. But no politician in his/her right mind is going to actually say that out loud.