From Cox and Forkum:
The criticism that Israel is using a "disproportionate response" to the kidnappings of its soldiers is an attempt to morally disarm Israel and make Israel out to be a bully. This notion is ludicrous when considered in the full context: Hezbollah and Hamas initiated the current crisis in an ongoing war against Israel's right to exist. Notice that no one cried "disproportionate response" when Hamas demanded 1,200 prisoners in exchange for one Israeli hostage. Hamas and Hezbollah aren't playing a game of proportions, why should Israel?
Israel, an outpost of freedom in the Middle East, has every right to use whatever means necessary for her long-term interests to defeat those who are warring against her. All the "disproportionate response" critics are accomplishing is to empower Israel's enemies to wage more war, harm more Israeli citizens and escalate the violence. They are kicking Israel when she is down, when she needs our support the most.
I think that about sums it up. Supporting Israel against these enemies of mankind is simply the right thing to do.