More than economic depression, recession or domestic affairs, war defines the presidencies of U.S. leaders who feel compelled or forced to wage it. Barack Obama has chosen to become one of them.
Few who voted for Mr. Obama, and fewer still among those who did not, could have imagined that the defining act of his first year in office would consist of an escalation of U.S. military engagement abroad.
But by sending another 30,000 U.S. troops to Afghanistan - on top of the 21,000 he dispatched last spring - this year's Nobel Peace Prize laureate will have tripled the American military presence there by the time the last of the reinforcements arrive in mid-2010.
"I make this decision because I am convinced that our security is at stake in Afghanistan and Pakistan. This is the epicentre of the violent extremism practised by al-Qaeda," Mr. Obama warned Tuesday night in a televised speech from the United States Military Academy at West Point, N.Y.
For a leader often criticized for being overly cautious, the Afghan surge is a muscular act that will undermine Republican criticism of Mr. Obama as weak-kneed - though the mechanical, at times listless, delivery with which the President laid out his strategy will nourish doubts on the right about his commitment to it.
"This does not look like political triangulation. He's giving [U.S. commander in Afghanistan General]Stanley McChrystal most of what he asked for," opined Charles Kupchan, a senior fellow at the Council on Foreign Relations and a professor of international affairs at Georgetown University in Washington. "If it is true that the Obama administration inherited this conflict, it has now put its imprint on it in an indelible way."
The price of failure could be Mr. Obama's presidency, just as entanglement in Iraq became George W. Bush's albatross. And most experts agree that success in Afghanistan is still not the most likely of outcomes.
War, especially of the counter-insurgency kind, is chaotic and no amount of deliberation or meticulous planning - in which Mr. Obama can be said to have engaged liberally - can control for a situation with as many moving parts as the powder keg known as Af-Pak.
By definitively tying his inchoate presidency to subduing the Taliban and depriving al Qaeda of a safe haven, Mr. Obama is the latest U.S. commander-in-chief to take up arms in support of a friendly - if seriously flawed - regime to achieve broader U.S. geopolitical goals.
If his decision-making process is more methodical and less instinctual than that of Mr. Bush, the end result is similar. It was Mr. Obama's predecessor who oversaw the "troop surge" in Iraq that has made the gradual withdrawal of U.S. soldiers from that country now possible.
The one big difference between presidents 43 and 44, however, is that Mr. Obama has publicly set out a timeline for drawing down U.S. troops in Afghanistan and handing off responsibility for national security to the domestic forces of what is supposed to become a functioning, if not quite peaceable, democracy.
Just how committed is Mr. Obama to seeing this strategy through if the timeline he laid out last night is not met? Republicans doubt that he has the stomach for sticking it out. But the voters to whom Mr. Obama owes his presidency will support a troop surge only if he promises to cut U.S. losses if his benchmarks aren't achieved by prescribed dates, and will do so begrudgingly at that. The danger is that domestic political exigencies force Mr. Obama to pull troops out prematurely.
"What I'm concerned about is that with so much attention being paid to what's going on [in the short-term]that things will go in the right direction, but once we lose our focus on Afghanistan, [progress]is going to be derailed," warned Karin von Hippel, a senior fellow at the Center for Strategic and International Studies in Washington.
Still, with the cost of the Afghan war set to explode to more than $100-billion annually with the surge, from the $20-billion spent in 2006, Americans increasingly feel their debt-strapped country cannot afford several more years of deep military involvement in a far-flung region.
But while there are probably as many first rules of warfare as there are generals, a strong candidate for second place among the axioms of armed conflict is this one: War respects no political calendar.
President Lyndon Baines Johnson tried to wage the Vietnam War according to the U.S. political cycle, postponing his own "troop surge" until after the 1964 election and betting U.S. withdrawal would have begun before the next one. He got it so wrong he didn't even bother running in 1968.
Now, Barack Obama is promising to begin drawing down U.S. troop levels from Afghanistan barely a year after all of the 30,000 reinforcements announced Tuesday will have arrived and a comfortable 16 months before Americans decide whether to give Mr. Obama four more years.
Mr. Obama, the commander-in-chief, must now prove he is no LBJ.