There are several such reasons:
Geopolitical: The United States support for the State of Israel comes from a variety of sources. Israel has cooperated with the United States on diplomatic issues, military and intelligence exchanges, large amounts of trade, and significant technological investment.
Religious: Many American Jews and Christians believe that God promised the Land of Israel to the Jews in The Bible and see it as an American Imperative to maintain Israel's Divinely Mandated Existence.
Values: Israel is a democratic nation with "First Amendment Freedoms". Its citizens are free to practice whatever religion they want, say whatever they choose, and feel no pressure or compulsion from anyone. This runs counter to most Arab States in the region which have anti-blasphemy, anti-apostasy, and anti-missionary laws. US Americans feel solidarity with other Liberal Democracies.
The Jewish Right to a State is a Legal Right: Israel is a legal state that the United States helped to form. In 1947, the British gave direct authority to the League of Nations' successor, the United Nations, in accordance with the terms of their Mandate. The UN passed the 1947 Partition Plan that gave both a Jewish State and an Arab State the Right to Declare Statehood. The fact that the Arabs decided not to immediately declare such a state does not make the Israeli declaration any less valid.
The United States does not have a right to the Israelis' homeland. There is nothing to defend.
The appeal of the mission - to defend the homeland against the invader.
A truly emotive war-mission - to defend the homeland against the invader.
The US and Israel are parties to mutual defense treaties, which presumably would be honored by both of them in case one or the other were in danger. You asked "should", so I'll add my opinion that it would definitely be the right thing to do.
The appeal of the mission - to defend the homeland against the invader.
Israel
The reasons Romans soldiers were stationed is because they were to defend there homeland from Barbarians attacking on them which would cause them to (raid) occupying the Romans cities.
No, while it is generally beleved that Israel does have Atomic weapons, this has never been confimed by Israel. Israel officially refuses to confirm or deny their existence.Meier did say Israel would use "every weapon available" to defend themselves.
He would state they would defend the right of the States and their way of life.
Answer 1In the Jewish Tanakh, God foretold that the lost tribes of Israel would one Day (Age) return to their homeland of Israel. There is a saying that God works in mysterious ways. If not for the Holocaust, would European Jews have fled to the Holy Land and would the world (U.N.) have been prepared to return a portion of Palestine to them and formalize the nation-state of Israel?
They would send them back to their homeland, if there was a war in there homeland, they would send them to Another Country.
Yes. That was one of the main reasons Israel was created, so that all Jews would be able to return to their homeland. It also allowed for the mass immigration of Mizrahi Jews that took place from 1950-1955, almost doubling Israel's workforce and making the Jewish majority a concrete fact in Israel.