Unrest in Hong Kong intensified the weekend of Aug. 10-11, with violent clashes between protesters and local police and security forces, which continued their crackdown. On Aug. 12, protesters overwhelmed the territory's international airport, leading to the cancellation of hundreds of flights. What Are Beijing's Red Lines, and How Might It Intervene? With the Chinese and Hong Kong governments refusing to yield to protesters' demands and Hong Kong police thus far proving incapable of restoring calm, no resolution is on the horizon. And this raises questions about just what would induce the mainland government to intervene directly in the special administrative region. On Aug. 12, a Chinese official said growing violence in Hong Kong, especially against the police, had begun showing characteristics of terrorism. He apparently was referring to the use of Molotov cocktails against the police and footage of a protester who appeared armed with an M320 grenade launcher.