By contrast, the older pan-democratic parties have had little new to offer. The Democratic Party’s political centerpiece in the recent election amounted to asking Beijing to reopen the door to electoral reform. The pan-democratic leaders, in sticking to what is widely viewed by the youth as a depleted strategy, have lost the trust and respect of younger people.

The separatists still face many challenges. Ideological fights within their camp have been bitter and divisive. And leaving aside the possibility of a military crackdown or severe retaliatory economic penalties against Hong Kong by Beijing, secession of the territory from the mainland would be impractical: China controls the bulk of the city’s food, water and much of its energy supply. Meanwhile, much of the Hong Kong public is wary of the youthful radicalism.

China’s leaders appear to think that taking a hard line against the separatist movement can contain it. A stern postelection statement from Beijing said the Hong Kong government should punish independence activists.

This strategy will backfire. It was the heavy-handed behavior of Leung Chun-ying, the pro-Beijing Hong Kong chief executive, that has fueled the separatist movement’s growth in the last two years. Mr. Leung singled out a separatist publication for public reprimand last year, angering Hong Kongers with what they saw as an implicit threat to free speech. He banned a student leader who supported independence from attending his university’s council meetings.

Direct interference from Beijing in local affairs has made matters worse. Last year, five workers at a Hong Kong publisher of provocative political books were kidnapped and brought to the mainland where they were detained.

It may be too late for China to convince the hard-core separatists to back down, but there are steps the leadership could take to stem the growth of the movement.

Beijing should remove its central government staff from Hong Kong. The Central Liaison Office has been blamed for many of Beijing’s illegal interventions in Hong Kong affairs. Pro-Beijing politicians are regularly seen visiting the office, giving the impression they take orders directly from the mainland. Shuttering it is an easy gesture that would remove a source of conflict.