"I don't think its going to be very fruitful to have a separate discussion with Hamas. Unless they give up this notion that they are going to continue to raise warfare against Israel, then I don't see any profit in talking with them, in negotiating with them," Cohen said.

If he is nominated and confirmed, Hagel will face the challenge of closing the final chapter on the U.S.-led war in Afghanistan and overseeing the continued footprint of a smaller U.S. training force there.

Hagel has been critical of U.S. policy in Afghanistan. In 2009 he opposed Obama's 30,000-troop surge, telling the National Journal, "I'm not sure we know what the hell we are doing in Afghanistan." "It's not sustainable at all; I think we're marking time as we slaughter more young people."

Later he called for the United States to stop its "nation-building" there.

"We are where we are today -- going into our 10th year in Afghanistan, our longest war -- because we did take our eye of the ball," he told the Washington Diplomat in 2010 after leaving the Senate. "We really made some big mistakes during that time. I have never believed you can go into any country and nation build, and unfortunately I think that's what we've gotten ourselves bogged down in."

Hagel has also spent time in Pakistan and co-chaired a 2009 Atlantic Council report with Sen. John Kerry that concluded that Pakistan faced, "dire economic and security threats that threaten both the existence of Pakistan as a democratic and stable state and the region as a whole."

"The U.S. also needs to urgently close the "Trust Deficit" between it and Pakistan, with greater exchanges of high-level visits, closer military, intelligence, and economic cooperation," according to the report.

The most immediate issue Hagel would face would be the future of the Pentagon's budget.

Just days before the United States reaches the edge of the "fiscal cliff" in which the Defense Department faces the loss of $500 billion on top of an already planned $500 billion in cuts, Hagel believes the Pentagon's budget is too big.

"The Defense Department, I think in many ways, has been bloated," Hagel said in a September interview with the Financial Times. "So I think the Pentagon needs to be pared down."

If Hagel becomes secretary of defense, he would have to have "great lines of communication" with members of Congress, who will oversee the Pentagon's smaller budget, Cohen said.