The 27 Bangladeshis arrested in Singapore under the Internal Security Act had supported the extremist ideology of terrorist groups such as Al-Qaeda and the Islamic State in Iraq and Syria.
Of the 27, 26 were members of a closed religious study group that subscribed to extremist beliefs and teachings of radical figures like the late Anwar al-Awlaki, an Islamic lecturer alleged to have ties with militant group Al-Qaeda.
Here are some things about the cleric:
1. Awlaki was born in the United States and was a US citizen. Due to his ability to speak fluent English, he built up a base of extremist followers while living in London for two years until 2004. He spent his final years in hiding in his ancestral land of Yemen.
2. Awlaki was killed by a US drone strike in the Yemeni town of Khashef, in the northern al-Jawf province bordering Saudi Arabia, in September 2011. Four other suspected Al-Qaeda members were killed alongside him in the raid.
3. Before his death, Awlaki was hunted by the US for years. He became the first American ever to make the Central Intelligence Agency's hit list after President Barack Obama approved an order last year to place him on it. His placing on the hit list sparked a debate due to his status as a US citizen.
4. Though he is dead, his legacy lives on in numerous videos on the Internet, where he teaches Muslims about various aspects of Islam. However, among these harmless tutorials are those with a darker message, for example on how the US is at war with Islam, how Muslims should kill Americans, and glorification of those behind attacks like the fatal shootings in Fort Hood in 2009.
His fiery sermons have inspired militants worldwide to commit violent terror attacks, including the July 5, 2005 bombings in London and several attempted attacks.
5. This is not the first time that Awlaki's teachings have radicalised people in Singapore. In 2010, Singaporean businessman Muhammad Thahir Shaik Dawood was placed on Restriction Order - meaning he cannot change jobs, move or leave Singapore without the approval of the director of the Internal Security Department. He had gone to Yemen to seek out Awlaki with the intention of joining fighters overseas, but failed to get in touch with him.
Muhammad Anwar Jailani, an unaccredited religious teacher, was also placed on Restriction Order for distributing CDs of Awlaki's lectures urging Muslims to undertake "militant jihad".
Muhammad Fadil Abdul Hamid, an NSman, was detained after initiating contact with Awlaki, saying he wanted to fight alongside him.