Honestly, don't worry about it.
Example: as much as I dislike the Vietnamese government, they would identify and shoot these suckers down in one millisecond. There is not going to be an attack on the U.S. Embassy Saigon. The idea is laughable and testament only to Islamist hubris (which will ultimately get them all killed, captured, or spilling their guts under the influence of Valium).
And the Cambodians would simply eat their livers for lunch. Islamists visiting Phnom Penh will immediately find themselves on the radar screens of several different governments. Yet despite being 95 percent Buddhist, Cambodia is also a warrior society and eating Islamist livers would be "the Khmer way" of doing justice.
They cannot hide in or infiltrate SE Asia. $500 US cash would eliminate them one by one, effectively, immediately, and anonymously.