MHA said family and friends are often the first to notice behavioural changes.
It said that in past cases, friends and family members had withheld information from authorities either out of denial or misguidedly believing that they are protecting their loved ones.
"The opposite is true,” it added. “The amorphous nature of the enemy we face today means that even though our security agencies will do what it takes to detect and prevent terrorist attacks, they cannot do so alone.”
At stake are not just property and lives, but Singapore’s identity as a multiracial, multi-religious society, MHA said, calling on people to play their part in keeping Singapore safe.
The report said the Internal Security Act had dealt with 14 radicalised Singaporeans since 2015.
"Among the recently detained Singaporeans, two of them said that they were prepared to carry out attacks in Singapore on behalf of ISIS. One of them said he wanted to assassinate the President and Prime Minister of Singapore so that the country would become leaderless and could be turned into an Islamic state under the 'Islamic caliphate'."
Mr Muhammad Faizal, a research fellow from the Centre of Excellence for National Security, said: "Singaporeans can use the Religious Rehabilitation Group (RRG) app or call the RRG helpline 1800-774 7747 if they have questions on radicalisation or suspect someone is radicalised."