PHILIPPINES - They see an armed conflict overseas as their own and they throw themselves into the fight.
Little do they realise the perils and complexities of the conflict.
That was the case with a Singaporean named Muhammad Ali Abd Al-Rahman.
In 2012, when bombs were dropped on Jolo island in the Philippines, 15 militants belonging to the Moro Islamic Liberation Front (MILF) were killed.
Among them was Muhammad Ali, also known by his guerrilla name, Mauwiyah.
Terrorism expert Rohan Gunaratna had described Mauwiyah as a trainer to hundreds of Philippine, Indonesian and Malaysian terrorist recruits.
Prof Gunaratna is head of the International Centre for Political Violence and Terrorism Research at the S. Rajaratnam School of International Studies in Singapore (RSIS).
Mauwiyah was not the only one to travel overseas to get involved in armed conflicts. More recently, another Singaporean, Haja Fakkurudeen Usman Ali, travelled to Syria with the intention of being a foreign fighter.
Haja, 37, a former Indian national who obtained his Singapore citizenship in 2008, had worked as supermarket manager. The Government announced his arrest last month.
Security expert Kumar Ramakrishna, also of RSIS, said: "Usually these individuals feel that their collective identity - be it ethnic, religious or nationalistic - is being attacked, although they themselves are not being attacked personally."
"These vicarious sentiments have been called moral outrage or social humiliation. They feel the need to defend their 'group tent'."
In Syria, for example, experts estimate that there are about 5,000 foreign fighters. And as of July 2013, the United Nations estimates that more than 100,000 people have been killed there, among them the foreigners fighters.
Many of these foreign fighters believe they are there to protect the innocent.