Before each game in Bosnia and Herzegovina’s World Cup adventure, Sarajevo has blossomed with primary colours – and two distinct flags.

One is the national flag dating to 1998: blue and yellow diagonal halves emblazoned with a slanting line of white stars. The other has golden lilies on a blue shield set against a white background, and has a far deeper history, steeped in centuries of complexity. Its striking resurgence as a national symbol, showcased during Bosnia’s first World Cup for 12 years, comes with its own powerful message.

“It’s basically a big FU,” said Reuf Bajrović, a former energy, mines and industry minister who is now vice-president of the US-Europe Alliance, an Atlanticist advocacy group. “It’s in great part the mass rejection of the international community and its policies.”

The lilies’ vivid comeback comes at a time of deepening uncertainty about Bosnia’s future. The country’s historical protector and closest ally, the US, has grown unreliable under the Trump administration, which has essentially switched sides and now appears to be supporting Serb separatists dedicated to Bosnia’s dismemberment. At the same time, Trump associates are scouting the region for lucrative business projects.

In such tense circumstances, national colours take on a special significance. The blue-yellow state flag, under which the national team has been playing in North America, was imposed by the international community in the aftermath of the Bosnian war, after the country’s three primary ethnic groups and former warring parties – Serbs, Croats and Bosniaks – failed to agree on mutually acceptable colours.

It has the deliberate blandness of a design chosen by committee, evoking little emotional attachment, but for nearly three decades it has been accepted by the predominantly Muslim Bosniaks, the country’s majority. (The term also encompasses secular and mixed-ethnicity citizens who embrace Bosnia as their primary identity.)

A foreign-imposed flag was accepted because it was foreign intervention, led by the US, that ended the three-year slaughter of the Bosnian conflict, which killed 100,000 people. More than 80% of them were Bosniaks, many of them murdered in mass atrocities including the 1995 Srebrenica genocide.

Also in the same spirit as the imposed flag, Bosniaks accepted the continued foreign stewardship of the country in the form of a high representative of the international community, sitting in Sarajevo with broad powers to intervene politically as he (and it has always been a he) saw fit. It was part of the price of peace, even though the 1995 Dayton peace deal enshrined the consequences of Serb ethnic cleansing by leaving half the country, the Republika Srpska, under Serb control.

More than a quarter-century has brought scant political progress. Republika Srpska still resists integration, and its extremist leader, Milorad Dodik, is an ally of Vladimir Putin who is blatantly unrepentant for the mass killings of the 90s.

As a symbol of the attempt to forge Bosnia as an integrated state, the official flag represents both tenacious hope and deep disappointment. “People were prepared to put up with the new flag as a price of international acceptance, but nobody actually identified with it,” said Ivana Marić, a political analyst in Sarajevo.

The lily flag resembles the fleur-de-lis of French Bourbon monarchy, but it has equally deep roots in Bosnia, based on an indigenous Bosnian flower and a medieval Bosnian kingdom. It was chosen as the flag of a reborn Bosnia and Herzegovina in 1992, as a shared historical, non-sectarian symbol, but in the conflict that followed independence it also became associated with the resistance effort of the mainly Muslim Bosnian army against the country’s predatory neighbours.

Its growing popularity among Bosniaks, particularly the young, reflects growing impatience with the status quo, and a desire to express an ethnic identity unconstrained by external forces.

“The Bosniaks have been willing to go along with whatever was done in the name of the international community and in the name of peace in the last 30 years, but that has oftentimes not worked,” Bajrović said. “The international community has instead favoured nationalist Serbs and Croats.”

Before Bosnia’s match against Switzerland, a senior Bosnian army officer was drinking coffee near one of the communal screens set up in Sarajevo for the World Cup. He reflected on the evolution of national symbols.

He is a Bosniak, and was wounded defending Sarajevo during the war with a Bosnian lily patch on his uniform, but rose through the ranks of a modern western-integrated national army under the blue and yellow flag. His teenage daughter, however, insists on going to games draped in the lily flag.

“For her, it is about pride in who we are as Bosniaks,” he said. “It is all defiance. If Serbs and Croats can display their ethnic symbols, why not us? This younger generation believes in the nation even more than we did.”

The Bosnian football team is itself an exercise in the frustrations of nation-building. There are seven Croats in the squad, but despite this, Bosnian Croat parties have suppressed celebration, or even recognition, of the squad in areas they control. In some places, big screens for communal watch parties have been banned.

The national team manager, Sergej Barbarez, comes from a family of Serbs, Croats and Bosniaks. But he managed to persuade only one Bosnian Serb to join the team in the face of strong nationalist pressure on young players to stay away.

Dodik was officially ousted from office last year, but he continues to hold sway in the Republika Srpska. Despite the fact that his own nephew runs the Bosnian football federation as a result of interethnic job sharing arrangements, he has quashed any official Serb support for the national team.

Aleksandar Trifunović, an independent journalist in Banja Luka, the biggest Serb city, said: “Here unfortunately, the national team and the World Cup are officially ignored. People do watch and follow the games, but there is no organised support or public fan gathering.”

Beneath the rigid cartoon-like versions of ethnic identity presented by the nationalist parties, popular attitudes are more nuanced.

Big crowds in Sarajevo have come out to cheer for Croatia, many in their Bosnian kit, seeing no contradiction. A few miles away, in East Sarajevo inside Republika Srpska, the streets are festooned with Serbian tricolours with not a Bosnian flag in sight. Near a municipal playground, there are stencilled images of Ratko Mladić, the Serb wartime army commander now serving a life term for genocide in a Dutch prison. But the young men whiling away time on cafe terraces said they would be watching Bosnia play and hoped they won. After all, one said, they are “domaći” (domestic).

Similarly in the mainly Croat town of Kiseljak (40km west of Sarajevo), the flag of the wartime ethno-statelet, Herzeg-Bosnia, is still flying 33 years after it sparked a short, bloody war-within-a-war between Bosniaks and Croats. A local bar, the Movie Café, was screening Croatia but not Bosnia games for fear of “provocations”, according to the bartender. But Stipo, a 40-year-old customer, said most people would cheer for the Bosnian team in the privacy of their own homes. “We are Croats, first and foremost, but we are Croats from Bosnia,” Stipo said.

In a nearby hookah cafe, Anes Hadžić, a 28 year-old from Kiseljak’s Bosniak minority, said the World Cup did sometimes bring up obnoxious behaviour in the town, like a local bar flying the Swiss flag before last week’s Bosnia match.

“That is why the lily is coming back. It’s a reaction,” said Hadžić. But he added: “Eighty per cent of the people here are fine. We work together and they will support Croatia and us, when we play.”

“It is the politicians who are happiest when we are divided, so they can sell our land and our water from under us,” Hadžić said. “After all, why preach about something good when you can start a fire?”