JAKARTA: Indonesian militant cleric Abu Bakar Bashir was jailed for 15 years Thursday for helping plan a paramilitary group that aimed to kill the country's president, a sentence that could inflame hardcore militants who had vowed revenge. Jailing Bashir, 72, considered the spiritual leader behind the group that killed more than 200 people in Bali in 2002, is an important step in government efforts to weaken terror groups, but may not reduce the threat of attacks. Bashir does not command widespread support in Indonesia, home to the world's largest Muslim community, but the guilty verdict could motivate groups which have already vowed reprisals after the US killing of Al-Qaeda leader Osama Bin Laden. “It will not affect the security risk, but it is still better to keep him from preaching hate speeches,” Ansyaad Mbai, the head of the counter-terrorism agency, told Reuters. “It is another step to stem the radicalization of more young people.” Underlining that risk, an anonymous text message circulating through the capital this week warned of 36 bombs exploding across the country the moment the judge in the south Jakarta court announced a guilty verdict. There was no sign of any immediate attacks, though security risk firm Concord Consulting said one person was arrested and bomb making equipment seized in central Java Thursday. Bashir was found guilty of helping plan and fund a paramilitary training camp discovered last year in a remote mountainous part of Aceh, whose members sought to assassinate the president, destabilise Southeast Asia's largest economy and turn the officially pluralist and mostly moderate Muslim country into an Islamic state. Bashir, who was acquitted on a charge of possessing weapons, had denied involvement in the plan. Indonesia has made progress tackling militant groups in recent years, killing many of their leaders, and political stability and strong growth have made it an emerging market favourite among investors, who have shrugged off security risks. Police stepped up security during the trial, with 2,900 officers at the court alone, where phone lines were scrambled and balaclava-wearing snipers took positions on surrounding buildings. The jail term is an effective life sentence for the frail cleric who has been active in Indonesian extremist circles for decades. He founded a boarding school in Java that produced several graduates linked to militant networks, including a man executed in 2008 for the 2002 Bali bombings. He used the trial to rail against perceived US influence in Indonesia. “I reject this unfair sentence...it is against Islam for me to accept it,” said Bashir, as women in burqas among his supporters wept. Men in headscarves jogged in a circle outside the court chanting: “The anti-terror detachment and the US are our enemies forever and ever.” Bashir's lawyer said he would appeal against the verdict. Police say Bashir was the spiritual leader of regional group Jemaah Islamiah, blamed for the 2002 Bali bombings that killed tourists in nightclubs, many of them Australian.