NEW-YORK, October 22. /TASS/. Last year's Boston Marathon terrorist attack shows that US intelligence agencies, in spite of carrying out large-scale electronic surveillance programs, make serious mistakes, former US intelligence agent Edward Snowden who leaked the secrets of National Security Agency to

mass media said during teleconference in Harvard University.

Snowden said that US intelligence missed the attack and that the investigation didn’t yield any tangible results because the US government has the strategy of collecting too much information at once. 

He stated that monitoring everyone at once prevents from seeing anything concrete because it is simply impossible to keep an eye on all targets at the same time. As an example, Snowden reminded of the Boston Marathon terrorist attack last year.

He reminded that Russian intelligence had recommended to take a note of Dzhokhar and Tamerlan Tsarnayev long before the bombings.

At the present time the US authorities have concluded that in April 2013 Tsarnaev brothers organized and carried out a terrorist attack in Boston downtown that killed 3 civilians and injured over 260 citizens. Later Tamerlan Tsarnayev was killed in officer-involved shooting. His brother Dzhokhar Tsarnayev is now awaiting trial.

He pointed out that US intelligence agencies have limited resources, so they have to decide whether they should spend $10 billion a year on large-scale NSA electronic surveillance programs if they don’t have an opportunity to carry out surveillance in the traditional way.