papakistan has b been plagued i- eliminateof vowed to the perpetrators of terrorist attacks. pakistan has been plagued by such attacks. linked to al qaeda. some are linked to the pakistani in the main area of the tribal belt close to afghanistan. all of them are connected in one way or another. it explains why it is so easy for the security force to be affected. reporter: some of the deadliest recent attacks include an assault in september when a -- in december when a gunman killed 148 people. september, a bomb in an airport base killed 29 people. targets have included civilian groups and military sites. host: back in europe, a man widely thought to be the third member of a group that bombed the ussels airport last week has been freed by belgian police. , and onwas identified saturday, he was charged with terrorist murder. but today, officials announced they did not have enough to justify holding him. he was released today. reporter: belgium is looking for this suspect, known as the man in the hat. footage near cctv the brussels airport right before it was rocked by explosion