Here's some recent history to ponder as the calls for military action against Iran intensify.

Ten years ago, President George W. Bush and top officials in his administration assured Americans that Saddam Hussein had weapons of mass destruction, and that a U.S. invasion of Iraq was justified and wouldn't be that difficult.

"Intelligence gathered by this and other governments leaves no doubt that the Iraq regime continues to possess and conceal some of the most lethal weapons ever devised," Bush said on the eve of the invasion.

The day before, Vice President Dick Cheney predicted American troops would "be greeted as liberators." Asked by Tim Russert of NBC if the administration was prepared "for a long, costly and bloody battle with significant American casualties," Cheney dismissed that possibility.

When the Army chief of staff, General Eric Shinseki, in congressional testimony, said "it would take on the order of several hundred thousand troops" to occupy Iraq, Deputy Defense Secretary Paul Wolfowitz, an architect of the war, dismissed the assertion as "outlandish." Shinseki was soon shown the door by the administration.

Wolfowitz later acknowledged that weapons of mass destruction were simply the easiest rationale to justify a war. "For bureaucratic reasons, we settled on one issue," he said.

It was a long and costly war with significant casualties and no weapons of mass destruction were found.

Four years ago Barack Obama, while not as severely off as his predecessor, made Afghanistan seem easier than it has proven to be. "I will make the fight against al-Qaeda and the Taliban the top priority it should be," he said. "This is a war that we have to win."

The Obama administration has decimated al-Qaeda and killed its leader, Osama bin Laden, but few say the war has been won.  And Afghanistan has not produced a victory against the Taliban as the president prepares for a gradual withdrawal within two years.

(Albert R. Hunt is Washington editor at Bloomberg News and a Bloomberg View columnist. Follow him on Twitter.)

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