To an interested albeit casual outside observer, politics in Bangladesh has long seemed a highly personalized duel between the leaders of the country's two main parties: Sheik Hasina of the Awami League, the current prime minister, and Khaleda Zia of the Bangladesh National Party (BNP). Punctuated by fairly regular charges of election fraud and nationwide strikes and boycotts, this rather dysfunctional political setting has not distinguished itself in recent months when faced with the challenge of rising jidahist-militant violence, including a string of fatal attacks on bloggers, academics, and others.
The attack on the restaurant in the Gulshan district of Dhaka, for which ISIS claimed responsibility and in which 20 people who had been taken hostage were killed, has led to renewed attention to what the current government has been doing -- or more to the point, not doing -- about the threat and actuality of militant violence. As Ishaan Tharoor notes in a July 2 WaPo piece (see esp. the links toward the end of the article), close observers have criticized Hasina's government for downplaying or denying the extremist threat and focusing too much effort on consolidating its power at the expense of the BNP. Until the government's basic approach changes, Bangladesh, which has been one of the Muslim world's relatively secular, as opposed to theocratic, polities, will probably continue to be seen by ISIS and other extremist groups as fertile ground for expansion.
ETA: See also this by J. Allchin, which goes into detail on the recent history and gives one a sense of the complexities of the political situation in Bangladesh.