Those who carried out the bombing may have been Indians or Srilankans or Japanese, or even the US or the Afghans themselves. When the word may is used, it becomes a supposition. Then your guess is as good as mine and you become as qualified as Admiral Mullen. In the end, Jalauddin Haqqani is an Afghan so an Afghan group were responsible foi the boom at the Indian Embassy at Kabul and connivance is a very difficult thing to prove.