No matter what the country, trespassing on a military base is asking for trouble. The pro-democracy activists who ignored a People's Liberation Army guard's warning and broke into the Central barracks at Admiralty on Boxing Day have committed a serious offence. Politics played a part in their actions - they were carrying colonial-era Hong Kong flags - but political groups have rightly condemned their protest. Those who have been arrested for such reckless behaviour have to be given an appropriate punishment. Four of the mostly-young protesters have been arrested and another is being investigated. They are members of Hong Kong Comes First, a group seeking government policies that give priority to citizens. The barracks occupies a prime harbour-front site that authorities want rezoned from public open space to exclusive military use. But politics has been added to the break-in through use of the colonial flag, a symbol of the fringe pro-independence movement, and at least one of the activists was a former member of the League of Social Democrats. But entering a military base with force is not about protecting the rights of Hong Kong people or making a political statement: purely and simply, it is breaking the law. Under the Public Order Ordinance, people who enter a "closed area" without permission face up to two years in prison. That is why, unusually, most of the pro-democracy parties and Beijing for once see eye-to-eye on an issue. The break-in has been viewed with "grave concern" by Beijing's Hong Kong and Macau Affairs Office while it has been condemned by pan-democrats, among them the movement's more radical elements. Hong Kong offers people who object to government proposals, policies and decisions a multitude of ways of expressing concern. Space is provided for open and fair discussion. In the case of the Central Barracks, the Town Planning Board has for a month been holding objection hearings before it makes a decision. Instead of breaking the law, that is the route the barracks protesters should have chosen.