JAKARTA (AFP) - Clad in camouflage and armed only with their convictions, the paramilitary wing of Indonesia's biggest Muslim organisation is on a campaign - to crush intolerance and defend the nation's inclusive brand of Islam.
The "militant moderates" from the Nahdlatul Ulama, which boasts 45 million members, are on the march as worries grow over the rise of ultra-conservative forces in the world's most populous Muslim country.
Hundreds of them swooped recently on a hotel hosting a meeting of a radical outfit, Hizb Ut-Tahrir, which wants to transform Indonesia into a "caliphate" run by syariah law.
They surrounded the building and forced an end to the meeting, before members were escorted away by police.
Ninety per cent of Indonesia's 255 million people are Muslim but the nation is home to substantial religious minorities and several faiths are officially recognised.
It is these traditions that the Nahdlatul Ulama (NU), which has existed for almost a century, is seeking to defend.
It has been taking a more muscular approach by increasingly sending out its paramilitary wing Banser to take on the hardliners.
"My forefathers the clerics, as well as Christians and others, established this republic together," Banser's national commander, Alfa Isnaeni, told AFP.
"We all need to defend this legacy."
The NU says it has felt compelled to step in and expand its activities in part due to the weakness of the government, which has long faced criticism for failing to crack down on ultra-conservatives.
There has been a growing number of attacks on minorities in Indonesia, from Muslim Shiites and Ahmadis to Christians, and concerns about intolerance surged after Jakarta's Christian governor was jailed for two years last month for blasphemy, in a case seen as politically motivated.
Indonesia is not governed by Islamic law, with the exception of western Aceh province, and efforts by hardliners to transform the archipelago into a syariah-ruled state have gained no traction.
There is little chance of this changing - a recent survey showed only one in 10 Indonesians support a caliphate - but the surge in intolerance has nevertheless caused jitters.
Members of Banser, which has a force about two million strong, do not carry arms but rely on sheer force of numbers to get their message across.
They confiscate banners and flags at rallies by hardline groups and hand them over to the police, justifying their actions by saying they are preventing conservative forces from trampling the country's inclusive ideology.
They also oppose Wahhabism, an ultra-conservative form of Islam that originates in Saudi Arabia, and have forced preachers who follow the doctrine off stage at public gatherings in some places.
Their battle cry is "N - K - R - I" - the Indonesian acronym for the term "the United State of the Indonesian Republic", highlighting their desire to keep the country together and strong.
"Anyone disagreeing with 'NKRI', or calling for a caliphate, will have to face us," Isnaeni said.
In recent weeks, they have also helped protect several members of the public targeted by hardline Muslim groups after posting anti-radical messages on social media.
The group holds rallies across Indonesia and has signed up thousands of new recruits to strengthen their efforts.
Global Islamic dialogue
The organisation is not just fighting radicalism in the street but also on a theological level.
NU youth wing Ansor wants to open dialogue with Islamic organisations and governments to build a global consensus among Muslims on adapting the interpretation of ancient Islamic laws known as "fiqh" so that they suit the modern world.
It wants recognition among Muslims that followers of Islam and others are equal, and a focus on the importance of the modern nation state and a constitution as guiding principles for a country, as opposed to syariah law.
The NU's efforts have sparked anger among conservatives, with some accusing them of being un-Islamic and defenders of non-Muslim "infidels" and Shi'ites, a Muslim minority regarded as a deviant sect by Indonesia's mostly Sunni Muslim population.
Greg Fealy, an expert on Islam from the Australian National University, praised NU's "impressive" efforts but warned: "I suspect real world political considerations and interests will prove a major obstacle to this being taken up internationally, let alone in Indonesia."
But NU's secretary general Yahya Cholil Staquf believes promoting a more moderate form of Islam is urgent to tackle hardliners.
"We must fight them before they cause more damage," he told AFP. "We will fight this to the end."