Hong Kong CNN  — 

Hong Kong’s summer of discontent has spilled over into fall, bringing with it tear gas, petrol bombs and widespread transport disruptions – all the elements that have divided the city during four months of unrest.

Observers had looked to China’s National Day on October 1 as a potential turning point for the protests, and since then they’ve escalated with protesters targeting businesses linked to mainland China.

The vandalism and violence poses a direct challenge to Chinese President Xi Jinping, who is not known for his tolerance of views that differ from the ruling Communist Party.

However, it is not clear if Beijing has a red line, and what it would take for protesters to cross it before provoking a Chinese military response.

Chinese military intervention in Hong Kong is still believed to be the last resort, as it would carry disastrous consequences for both the territory and mainland China.

But experts say the Hong Kong government’s failed efforts to stop the protests by evoking emergency powers could move Hong Kong closer to a more aggressive response from Beijing.