THE president who won the Nobel Peace Prize less than nine months after his inauguration has turned out to be one of the most militarily aggressive American leaders in decades.


Liberals helped to elect Barack Obama in part because of his opposition to the Iraq war, and probably don’t celebrate all of the president’s many military accomplishments. But they are sizable.


Mr. Obama decimated Al Qaeda’s leadership. He overthrew the Libyan dictator. He ramped up drone attacks in Pakistan, waged effective covert wars in Yemen and Somalia and authorized a threefold increase in the number of American troops in Afghanistan. He became the first president to authorize the assassination of a United States citizen, Anwar al-Awlaki, who was born in New Mexico and played an operational role in Al Qaeda, and was killed in an American drone strike in Yemen. And, of course, Mr. Obama ordered and oversaw the Navy SEAL raid that killed Osama bin Laden.


Ironically, the president used the Nobel Peace Prize acceptance speech as an occasion to articulate his philosophy of war. He made it very clear that his opposition to the Iraq war didn’t mean that he embraced pacifism — not at all.


“I face the world as it is, and cannot stand idle in the face of threats to the American people,” the president told the Nobel committee — and the world. “For make no mistake: Evil does exist in the world. A nonviolent movement could not have halted Hitler’s armies. Negotiations cannot convince Al Qaeda’s leaders to lay down their arms. To say that force is sometimes necessary is not a call to cynicism — it is a recognition of history, the imperfections of man, and the limits of reason.”


If those on the left were listening, they didn’t seem to care. The left, which had loudly condemned George W. Bush for waterboarding and due process violations at Guantánamo, was relatively quiet when the Obama administration, acting as judge and executioner, ordered more than 250 drone strikes in Pakistan since 2009, during which at least 1,400 lives were lost.


Mr. Obama’s readiness to use force — and his military record — have won him little support from the right. Despite countervailing evidence, most conservatives view the president as some kind of peacenik. From both the right and left, there has been a continuing, dramatic cognitive disconnect between Mr. Obama’s record and the public perception of his leadership: despite his demonstrated willingness to use force, neither side regards him as the warrior president he is.


Mr. Obama had firsthand experience of military efficacy and precision early in his presidency. Three months after his inauguration, Somali pirates held Richard Phillips, the American captain of the Maersk Alabama, hostage in the Indian Ocean. Authorized to use deadly force if Captain Phillips’s life was in danger, Navy SEALs parachuted to a nearby warship, and three sharpshooters, firing at night from a distance of 100 feet, killed the pirates without harming Captain Phillips.


“GREAT job,” Mr. Obama told William H. McRaven, the then vice admiral who oversaw the daring rescue mission and later the Bin Laden operation in Abbottabad, Pakistan. The SEAL rescue was the president’s first high-stakes decision involving the secretive counterterrorism units. But he would rely increasingly upon their capacities in the coming years.


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.