The United States government expected that Islamic State (ISIS) would target Brussels for its next attack, according to officials, but without precise intelligence information it was unable to prevent Tuesday's tragedy.
Three separate officials told Reuters that the US predicted ISIS would attack Belgium, but it could not know when or where it would do so.
The believed impetus for the strike was the arrest of Salah Abdeslam in Belgium last Friday. Abdeslam was the main suspect to have survived the ISIS attack on Paris in November.
While this could have influenced the timing, the US believes that the terror group was already planning an attack on Belgium and merely advanced the date.
In today's attacks, which struck a subway station and an airport, the jihadists murdered 34 people and left nearly 200 wounded.