Tourists walk by as Thai soldiers stand alert facing the sea outside the venue of the upcoming 15th Association of Southeast Asian Nations (Asean) Summit in the southern Thai resort town of Hua Hin yesterday.  Thailand is implementing a security lockdown at this weekend’s summit of Asian leaders with observers warning it cannot afford a repeat of chaotic scenes that saw two previous meetings cancelled. The nation, currently chairing the 10-nation Aseab, is mobilising an 18,000-strong security force and invoking a harsh internal security act to prevent protests in the resort town.