The IRA kidnap two British soldiers in Northern Ireland. They also bomb/assassinate some Protestant areas.
The UK responds by bombing Dublin Airport and then launching a ground assault, naval and air blockade and continued shelling on both Dublin and a number of other cities within the the Republic of Ireland that are believed to have IRA sympathies or groups.
The IRA repsonds by repeated shelling of both military and Protestant areas in Northern Ireland.
The Irish President calls on the British to stop bombing his/her county and killing civilians. The UK says it's fighting terrorism and the Irish Government should do more to disarm/wipe out the IRA.
Now tell me that Israel's response is justified.
(OK, the above is over simplified but the basics remain the same)