I read the article at a local paper here.

The problem with the river pirates there is that they are in the infra-structure, you are not only fighting the pirates, but the pirates families, the entire country by default.
Much like Iraq/Afghanistan.

Things are not as simple as they seem. - They could always go in there gun blazing, but it wouldn't make much difference in the big picture, its like putting a band-aid on a decapitation.

------
edited:
As an afterthought, the captain of the captured vessel is dead, of heart failure - the Pirates refused to let him go. So things in this particular instance might change quite rapidly.

__________________
Arguing on the internet is like competing in the special Olympics - You may win, but you are still retarded