A leading radical Islamic cleric, whom the United States had pressed Indonesia to prosecute aggressively for the past decade, was convicted Thursday of supporting a jihadi training camp after a four-month trial on terrorism charges. The cleric, Abu Bakar Bashir, 72, was sentenced to 15 years in prison. A district court delivered the verdict in Mr. Bashirs trial as thousands of extra police officers and hundreds of soldiers fanned out across Jakarta, the Indonesian capital, on a workday. In recent days, the authorities had been alerted to vague threats of a bombing campaign to coincide with the ruling. Jeers from his supporters outside the courthouse could be heard when the chief judged announced the sentence Thursday afternoon, but no incidents were reported in the city.