Gates: Bin Laden decision had big risks

“What I think people don't realize, and what made the decision tough for the president, was we didn't have one single piece of hard data that he was actually in that compound, not one,” Gates said. “The whole thing was a circumstantial case built by analysts at the C.I.A.”

Gates said he was primarily concerned with backlash from Pakistan, particularly if it turned out bin Laden was not at the compound.

“If this mission had failed, it could've put the war in Iraq, in Afghanistan, at risk,” Gates said. “And that was one of my principle concerns.”

The decision to kill bin Laden turned into a campaign issue earlier this month after the Obama campaign released a video implying that presumptive GOP nominee Mitt Romney would not have made the same decision.

Romney responded that it was an easy call, and Republicans blasted Obama for politicizing bin Laden’s death.

Gates, who was Defense secretary for President Bush and Obama, didn’t wade into the political fight over the bin Laden raid, but he laid out the reasons why he, as well as Vice President Joe BidenJoseph (Joe) Robinette BidenDemocrats will need to explain if they shut government down over illegal immigration Trump thinks he could easily beat Sanders in 2020 match-up: report Biden marks MLK Day: Americans are 'living through a battle for the soul of this nation' MORE, were opposed to the operation.

He said the concern about using a missile attack instead of the Navy SEAL raid was the inability to collect intelligence information and to be sure that bin Laden had been killed.

“My view was you'll know,” Gates said. “It may take a few months, and it's not as dramatic, and you won't get the headline that you will a SEAL raid.”

Of Obama’s decision to go forward with the raid, Gates said: “I’ve always thought it was a very courageous call.”