Sigit Indrajit, 23, confessed to planning the failed attempt to bomb the Myanmar embassy in May, saying it was in retaliation for the deaths of Rohingya Muslims in western Myanmar.
The BBC reported that Indrajit's lawyer, Akhyar, said his client had no regrets.
"He didn't feel any remorse because that's his ideology. He believes what he did was the right thing to do," Akhyar told the BBC.
Indrajit is the third man to be jailed in the bomb plot police uncovered after they arrested two people riding a motorbike toward the Myanmar embassy.
Police said five homemade bombs were found in a backpack carried by the men and other explosive materials were found in a house they rented.
Indrajit and the two men met on Facebook where they openly discussed plans to attack the embassy, the BBC reported.
Tensions between Muslims and Buddhists in Southeast Asia have risen since communal clashes in Myanmar and a resulting flood of Rohingya Muslim refugees to neighboring countries, including Indonesia.
About 200 people died in 2012 when clashes broke out between ethnic Arakanese Buddhists and Rohingya Muslims in Rakhine state, which borders Bangladesh, in 2012.
Buddhists and Muslims also have clashed in central Myanmar.
Rohingya are related to the Chittagonian Bengali across the border in Bangladesh and are distinct from the majority Buddhist population of Myanmar, who are of Southeast Asian origin.
A major issue has been the Myanmar government's insistence Rohingyas aren't Myanmar citizens -- disenfranchisement cuts off Rohingyas from job opportunities.
Bangladesh has received the majority of Rohingya fleeing by land and thousands remain in crowded refugee camps near the border. Many have fled by boat to other Asian countries, including Indonesia and Malaysia.
The Jakarta Post reported in April refugee camp authorities had to separate Buddhist and Rohingya detainees to avoid clashes, sometimes fatal.
The decision came after eight Buddhist fishermen at an immigration detention center in Belawan in northern Sumatra died in a brawl that started because of alleged sexual harassment of a female Muslim refugee, the Post reported at the time.
At the immigration detention house near the city of Tanjung Pinang, in the Riau Islands province, the house warden told The Post 59 Rohingya Muslims were being held in separate areas from 23 Buddhists.
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