Belgium has been gripped by the hunt for the heavily-armed renegade soldier Jürgen Conings for more than three weeks. Each day his disappearance exposes uncomfortable truths about European far-right extremism that have loomed over my reporting in Brussels.

Like others across the country, I have followed daily developments in the search for the 46-year-old corporal and specialist marksman who absconded from his barracks on May 17 with a small arsenal. Investigators found his abandoned car booby-trapped and loaded with weapons including four anti-tank missile launchers, but the man himself had vanished.

Alarm grew when it emerged that Conings was on an anti-terror watchlist because of his extreme rightwing views, including racist statements and threats made on Facebook. Potential targets, such as mosques, took precautionary measures after justice minister Vincent Van Quickenborne said Conings had lurked near the home of someone he had threatened. The case even intersected with the pandemic: Marc van Ranst, a high-profile virologist who had previously been menaced by Conings, was moved to a safe house.

The case has raised concerns familiar to many Belgians, including over the effect of regional divisions on the functioning of the state. Prime Minister Alexander De Croo is among those who have asked why Conings had access to such an array of arms, despite being under surveillance.

The affair has also laid bare political questions that have disturbed me since I returned to Europe after postings in south-east Asia, the Middle East and west Africa. The growing popularity of extremist European parties hostile to migrants from places I have worked is at odds with the rhetoric of inclusiveness from EU institutions in Brussels.

The disappearing soldier has added to wider European fears about far-right activity in national militaries. In April, hundreds of French army pensioners, along with at least 18 serving personnel, wrote an open letter warning that France was “in peril”. The statement cited the dangers of “Islamism” and “the hordes” in suburbs with large immigrant populations. It was the brainchild of a former head of security for the ex-National Front leader Jean-Marie Le Pen — and was endorsed by his daughter Marine, the main challenger to President Emmanuel Macron.

In Germany, a series of cases involving soldiers alleged to be far-right sympathisers has raised concerns about the reach of such extremism. Last month the trial began of an officer accused of posing as a Syrian refugee and plotting attacks on politicians.

Far-right parties in Europe, such as the Alternative for Germany (AfD), have appealed for support from military personnel, says Claudia Major, a defence analyst at the German Institute for International and Security Affairs. “The AfD has really tried to position itself as the party of the soldiers,” she says. “Armies tend to attract conservative people — but there is a step from conservative to reactionary.”

The Conings case has also highlighted the wider penetration of far-right politics in some parts of Europe. Significant support for the Awol corporal has emerged on social media. A Facebook group called “As 1 Behind Jürgen” attracted more than 40,000 members before it was removed.

Support for hard-right nationalism has soared in Flanders, where Conings was based. He was a lapsed member of Vlaams Belang — “Flemish Interest” — a xenophobic, anti-Muslim Flemish separatist party that polls suggest is the region’s most popular party.

Vlaams Belang has attempted to distance itself from the soldier without disavowing his ideology. Chris Janssens, party vice-president, tweeted on Wednesday that Flemish authorities had failed to connect with the “growing segment of the population that does not agree with the policies of mass immigration and Islamisation”.

Meanwhile, the authorities continue to comb the country for Conings. The soldier remains elusive — but he is casting a dark shadow over Belgian public life.