The deadly attacks Thursday in the Indonesian capital, Jakarta, were not a complete surprise to Indonesian authorities, who warned last month of a credible threat.

The government deployed 150,000 security personnel to safeguard churches, airports and other public places across the predominantly Muslim nation, and made a series of pre-emptive arrests.

No one has claimed responsibility for Thursday's bomb attacks.

The authorities have been keenly aware of the danger of terrorism since bombings in 2002 on the resort island of Bali killed more than 200 people, more than half of them foreign tourists.

Islamist radicals have been blamed for a number of attacks around the country since the Bali bombings, which were attributed to Jemaah Islamiyah, an al-Qaida-linked Southeast Asian group.