Any international flight to the US can be subjected to security screening at the gate. Not limited to Asia airports - I have also seen gate screenings at Europe airports. Methods vary - sometimes full screening, other times only search carry on bags; sometimes everyone is searched, sometimes people are randomly selected, and sometimes no gate screening. Regardless of how screening is done, any liquids over 3 ounces are confiscated. Best thing to do is be prepared - have no liquids over 3 ounces unless you can confirm your flight isn't subject to the gate screening.