Soon after Mr. Obama took office he reframed the fight against terrorism. Liberals wanted to cast anti-terrorism efforts in terms of global law enforcement — rather than war. The president didn’t choose this path and instead declared “war against Al Qaeda and its allies.” In switching rhetorical gears, Mr. Obama abandoned Mr. Bush’s vague and open-ended fight against terrorism in favor of a war with particular, violent jihadists.

The rhetorical shift had dramatic — non-rhetorical — consequences. Compare Mr. Obama’s use of drone strikes with that of his predecessor. During the Bush administration, there was an American drone attack in Pakistan every 43 days; during the first two years of the Obama administration, there was a drone strike there every four days. And two years into his presidency, the Nobel Peace Prize-winning president was engaged in conflicts in six Muslim countries: Iraq, Afghanistan, Pakistan, Somalia, Yemen and Libya. The man who went to Washington as an “antiwar” president was more Teddy Roosevelt than Jimmy Carter.

Consider the comparative speed with which Mr. Obama and his Democratic predecessor, Bill Clinton, opted for military intervention in various conflicts. Hesitant, perhaps, because of the Black Hawk Down disaster in Somalia in 1993, Mr. Clinton did nothing to stop what, at least by 1994, was evidently a genocidal campaign in Rwanda. And Bosnia was on the verge of genocidal collapse before Mr. Clinton decided — after two years of dithering — to intervene in that troubled area in the mid-1990s. In contrast, it took Mr. Obama only a few weeks to act in Libya in the spring of 2011 when Col. Muammar el-Qaddafi threatened to massacre large portions of the Libyan population. Mr. Obama went to the United Nations and NATO and set in motion the military campaign — roundly criticized by the left and the right — that toppled the Libyan dictator.

None of this should have surprised anyone who had paid close attention to what Mr. Obama said about the use of force during his presidential campaign. In an August 2007 speech on national security, he put the nation — and the world — on alert: “If we have actionable intelligence about high-value terrorist targets and President Musharraf won’t act, we will,” he said, referring to Pervez Musharraf, then president of Pakistan. He added, “I will not hesitate to use military force to take out terrorists who pose a direct threat to America.”

That’s about as clear a statement as can be. But Republicans and Democrats blasted Mr. Obama with equal intensity for suggesting that he would authorize unilateral military action in Pakistan to kill Bin Laden or other Al Qaeda leaders.