A Democratic president has nominated a former Republican senator to be his Secretary of Defense. That would generally be a sign of a welcome bipartisanship on U.S. military and foreign policies.

But in the specific case of Chuck Hagel, whom President Obama named Monday as his choice to replace Leon Panetta at the Pentagon, it exacerbates familiar concerns that this administration is soft on Iran and hard on Israel.

During two terms (1997-2009) in the U.S. Senate from Nebraska, Mr. Hagel often opposed economic sanctions on Iran — even as it persisted as a major state sponsor of terrorism and pressed its ongoing pursuit of a nuclear arsenal.

He was one of only 12 senators who refused to sign a 2006 letter to the European Union attempting to accurately classify Lebanon-based Hezbollah as a terrorist organization. He opposed President George W. Bush’s ultimately successful 2007 “surge” strategy in Iraq.

Mr. Hagel also has insisted that Israel negotiate directly with Hamas, the Palestinian terrorist organization that now runs the Gaza Strip.

In 2006, then-Sen. Hagel even said of Israel’s influence on Capitol Hill: “The Jewish lobby intimidates a lot of people up here. ... I’m a United States senator. I’m not an Israeli senator.”

Several Republican senators, including our own Lindsey Graham, rightly cite that record as ample reason to oppose Mr. Hagel’s confirmation.

Sen. Graham said Sunday on CNN’s “State of the Union”: “This is an in-your-face nomination by the president to all of us who are supportive of Israel.”

Sen. Graham drew a sharp contrast between the president’s selections of a Republican for Secretary of Defense (Mr. Hagel) and a Democrat for Secretary of State (John Kerry):

“I expect the president to nominate people different than I would think. I’m going to vote for Senator Kerry. I don’t agree with him a lot, but I think he’s very much in the mainstream of thought. Chuck Hagel, if confirmed to be secretary of defense, would be the most antagonistic secretary of defense towards the state of Israel in our nation’s history.”

No, the U.S. should not back every move by every Israeli government. That would be a disservice to Israel by its closest international friend.

For instance, Israeli Prime Minister Benjamin Netanyahu’s plan to expand settlements on the West Bank deserves the negative reaction it has drawn from the White House. It threatens any hope for a lasting accord and gives Hamas potent propaganda ammunition.

Mr. Hagel does have firsthand knowledge about the sacrifices paid by our the brave men and women of our armed forces: He’s a decorated Vietnam combat Army veteran.

However, the Senate shouldn’t confirm Mr. Hagel unless he assuages warranted unease about his controversial past senatorial positions — and offers a more positive vision about the future of the Defense Department and its role in advancing U.S. aims.The stances he has taken on Iran, Israel, terrorism and other foreign-policy issues threaten those goals.

Mr. Hagel has some major explaining to do in his quest to secure Senate confirmation.