Jakarta, Indonesia (CNN) -- Indonesia's Supreme Court upheld the 15-year sentence of Abu Bakar Bashir, the firebrand cleric convicted of setting up a militant training camp in Aceh province.
Prosecutors accused Bashir of bringing together members of several extremist groups to set up the camp. They said the militants were preparing to launch assassination attacks on Indonesian government and police officials.
He was convicted in June 2011. In October, a high court reduced his 15-year sentence to nine years, on appeal.
The court said Bashir was only proven to have provided funds for the camp and deserved a more lenient sentence, partly because of his age.
The 73-year-old cleric had been tried three times since the 2002 bombings in Bali that killed more than 200 people, but was only directly linked to terrorism in the most recent trial.
Bashir was regarded as the spiritual leader and a founder of the Jemaah Islamiyah (JI), the terror network blamed for Indonesia's major terror attacks. He is accused of inspiring many of those involved in the bombings, which included attacks on Jakarta's JW Marriott Hotel (2003) and the Australian Embassy (2004) that left 22 people dead and about 300 injured.
He has consistently denied all the terrorism charges leveled against him and blamed the U.S. government backed conspiracy to keep him behind bars.
One of Bashir's lawyers, Adnan Wirawan, claimed via text message to CNN "that the decision is made based on political consideration" to satisfy the administration of U.S. President Barack Obama.
Wirawan had called the legal arguments and evidence "insufficient ... to support such (a) harsh sentence."
Last week the U.S. State Department classified the Jemah Anshorut Tauhid (JAT), the organization Bashir founded in 2008, as a terrorist organization. In a press statement, the State Department said JAT "is responsible for multiple coordinated attacks against innocent civilians, police, and military personnel in Indonesia."
The U.S. Treasury Department also designated three JAT leaders -- acting emir Mochammad Achwan, spokesperson Son Hadi bin Muhadjir, and leadership figure Abdul Rosyid Ridho Ba'asyir -- as being involved in recruiting and fundraising activities.
Son Hadi, one of those designated by the Treasury Department, said last week's announcement was a clear sign of U.S. pressure and intervention in Bashir's case.
"We suspected that the Supreme Court's decision would turn out this way because of that announcement. It clearly shows the pressure from the U.S. is very strong," he said.
Bashir's lawyer Wirawan said they plan to appeal the decision through a judicial review. If that fails, a presidential pardon will be Bashir's last option. However, "my client would rather drop dead than to beg for a pardon to the President," Wirawan said.