I'm not saying the Israeli's don't have political influence. Fabian Socialists and even Leftist Jews hate Israel and want to see it collapse. The issue in this particular case isn't really about any of those factions. We have military objectives, and one of those is the support of Israel against several Arab states. Israel is a friendly nation in MENA, which happens to be generally hostile. So, we conduct exercises with them.

And we have stayed back while Israel has been invaded before. Actually: every time Israel has been invaded US troops were not deployed.

• In the Yom Kippur War, US troops were not involved in any meaningful way.
• In the 6 Day war, the Israeli's explicitly lied to US diplomatic and intelligence sources about the likelihood of the war (which is why the USS Liberty was out there in the first place)
• No US forces were sent to aid Israel during the Arab-Israeli War
• No US forces were sent to aid Israel during the Suez Crisis (and we actually found ourselves in opposition to Israel & the UK)
• No US forces were sent to Israel while Saddam was launching SCUDs at Israel. Instead we sent them the pre-cursor to the Iorn Dome: the Patriot missile defense system (which was mostly hit/miss or for show).
• In an famous but memory-holed incident just before the Lebanese Civil War, a US Marine who was under Peacekeeping orders by the UN & Reagan admin put a 1911 to the head of an Israeli Tank Commander and told him to turn his armored column to turn around rather than proceeding further into Lebanon (as Israel was formally not allowed to invade Lebanon yet in "self defense" against Hezbollah).

This is mostly because, as I've said before, Israel is not our greatest ally. She is a staunchly independent country that has no real allegiance to the US or it's interests, and there's a reason she's not in the 5 EYES.

Though we are on friendly terms, and Israel would like to keep it that way, we have never been that close. The relationship has often been tense, terse, or subtly antagonistic.