It’s important to note here that Israel also undertook a military operation, seeking to arrest a Palestinian Islamic Jihad leader in the West Bank (and killing him when he shot at soldiers), not Gaza. The Hamas-Israel deal was for a halt to attacks by both sides in and around Gaza, not the West Bank, so technically this was not a violation of the agreement by Israel, though it was hardly a wise move.

If I had to guess, I would say the mortar fire on Sderot was “retaliation” by PIJ for the operation against its militants in the West Bank, and probably an effort to draw the other Palestinian factions back into a fight with Israel in Gaza. That would magnify PIJ’s apparent importance relative to Hamas, which bears responsibility for enforcing the “lull” among Palestinian groups in Gaza.

I doubt very much this was sanctioned by Hamas. It would be hard to imagine what Hamas would have to gain from a few isolated attacks like these. It certainly has proven its capacity and willingness to do battle with Israel, and the latest “lull” would have been its first diplomatic victory, and maybe even the beginnings of some broader international recognition and legitimacy.