Thailand's political crisis pits the electorally popular government, which draws its support mainly from the rural poor, against an elite in Bangkok, the army and the royal palace who fear a threat to their traditional power.
The anti-government protest movement, which calls itself the People's Alliance for Democracy (PAD), has said it would welcome a coup.
Protests by the PAD preceded the last coup, which overthrew the populist government of Thaksin Shinawatra in 2006.
Dr Giles Ungpakorn, a Thai political scientist, pointed out that the army is responsible for security at Suvarnabhumi airport and that Don Muang is located inside an air force base, yet the military did nothing to stop the PAD taking them over.
