Going HKG to GUM, we cleared security, but had a several hour wait due to a flight delay. We picked up a few bottles of water post security for the plane. After they finally started boarding, we walked down the jetway. Just prior to getting on the plane there was a security officer there who went through our bag, confiscating our water bottle. I thought it was odd, since we had already cleared security, but figured it was only done on US bound flights.