The warnings by our Government on potential terrorist attacks here must be taken very seriously.

The police and security forces are prepared and geared to do their utmost to protect residents.

However, it is vital that our people and communities be engaged and report potential threats, including possible radicalisation of individuals ("Efforts to fight terrorism 'must involve every Singaporean'"; July 23).

The Islamic State in Iraq and Syria (ISIS) has been known to prefer radicalised local adherents to carry out its dastardly acts.

The group's propaganda has become highly sophisticated and is frequently aimed at attracting locals, including young people.

Here is where the danger lies: That a few gullible young people may be attracted and instantly radicalised and motivated to carry out "lone wolf" copy-cat attacks. They could aspire to "glorify" themselves as the first to create mayhem in the country.

We should never be complacent and rely solely on our police and security forces to combat such threats.

ISIS is expanding its terror network and activities not only in Bangladesh, the United States and Europe, but also in Indonesia, the Philippines and Malaysia.

Its foreign fighters are trained, tested and beginning to return to their respective countries. A club in Puchong, Selangor, was recently struck by a grenade in an ISIS attack ("KL police see ISIS hand in grenade attack on bar"; July 5).

There have been several arrests in Malaysia and Indonesia, but the terrorist network appears to be very versatile. The southern Philippines has been designated the hub for its caliphate in South-east Asia ("No underestimating tentacles of terror"; July 11).

Our communities must never take things for granted. We have had our share of fanatics, like in the Jemaah Islamiah network, and there could still be gullible adherents in our midst.

The enemy from within is always more dangerous than the one from without. It is vital to be on the alert, and much better to be safe than sorry.

Adrian Villanueva