President Obama’s decision on the size and timing of the troop withdrawals from Afghanistan – bringing home 10,000 by the end of this year and 20,000 more by the end of the summer of 2012 – is pure politics.

Why should that surprise us?

His initial decision 18 months ago to “surge” American forces in Afghanistan by 30,000 – the amount he is now withdrawing -- was also inherently political.

During the election, Obama never stopped touting the war in Afghanistan as the “essential” conflict that President Bush had ignored to wage his war of “choice” in Iraq. So after taking office and a tortuous eight-month review, he finally fulfilled his campaign pledge to give higher priority to destroying Al Qaeda and its Taliban allies by agreeing to send an additional 30,000 forces to Afghanistan. But when he announced his surge decision in a speech at West Point in late 2009, Obama gave himself an out: he pledged to begin withdrawing the surge forces, in effect, “de-surging” at the end of 18 months.

The time had come. The president had to decide how quickly to implement his pledge. The decision, initially disclosed almost three weeks ago in a Daily Beast column by the well-connected foreign affairs guru, Leslie H. Gelb, was to withdraw all of the surge forces, but slowly over the next 18 months. The call was vintage Obama. The president tried to compromise, splitting the difference.

As a result, everyone got something he wanted and had to live with something he opposed. Those Democrats and Republicans who wanted to withdraw most of the American forces in Afghanistan ASAP – the “quick exiters,” as Gelb called them –got the big withdrawal they wanted. The “die harders,” or those opposed to pulling the extra capacity out of Afghanistan, got 18 more months and two more summer fighting seasons, minus one fall, to weaken the Taliban further. “Ain’t democracy grand?” Mr. Gelb declared.

The center ground seems to have few supporters. Obama’s 12-minute speech was soon denounced not only by Republicans, who have suddenly rediscovered their isolationist roots, but also by Democrats who believe that nation-building in Afghanistan is a waste of precious American blood and toil and resources that are badly needed at home.

Least unhappy with the president’s call were those like Vice President Joe Biden who have long argued that destroying Al Qaeda and keeping the Taliban from returning to power in Kabul can best be accomplished by deploying special forces and by targeted raids and drone attacks on militant havens in Afghanistan and neighboring Pakistan.

Echoing this view, Ann Marlowe, an Afghan expert and frequent visitor there, noted that the surge had actually increased the levels of violence in Afghanistan and hence, potential support for the Taliban. There has been a direct correlation between the surge in forces and growth in IED attacks. In 2010, she reported, Afghan insurgents planted 14,661 IEDs, a 62 percent increase over 2009’s 7,228, which was a 120 percent increase over 2008. “More troops means more IEDs, period,’ and hence, more injuries and death for American fighters. But while Marlowe applauded what she called the “excellent idea” of reversing the Afghan surge, she, too, lambasted Obama for not saying “we were wrong, I was wrong, we have learned something.”

Also bordering on the openly critical was the U.S military’s top brass. Testifying before a House committee, Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said that the President’s decision was hastier and creating "more risk" than he had advised. Ouch. He had counseled what he called a less “aggressive” approach, the same phrase, interestingly, that Gen. David Petraeus used to describe his assessment of the president’s decision in his confirmation hearings before a Senate committee for his new post of CIA director. But whatever General Petraeus’ reservations of the decision may be, he was quick to add that he would salute the president’s decision and head back to Afghanistan to begin implementing it immediately.

Usually, the desires to compromise and split differences are highly regarded in politics. Indeed, Les Gelb ultimately supported Obama’s call and said those who accuse him of abandoning Afghanistan – with 70,000 U.S. forces still on the ground – should “seek psychiatric help.”

But our politics and policy have become so polarized that the president is no longer given the benefit of the doubt by many Americans. When seen through the lens of the next presidential campaign and his determination to be elected, skepticism about his underlying motives and cynicism about tough foreign policy and national security calls will inevitably grow.

Mr. Obama could defuse some of this if he were more honest with the American people, if just occasionally, he acknowledged having made mistakes, or if he ever credited his predecessor with having made a wise call instead of repeatedly bashing him and blaming him for all of the challenges he now confronts. There is one unmistakable irony in the course the president has chosen. The strategy as espoused by Mr. Obama Thursday this week is not that different from the one initially embraced by former President George W. Bush. “After a decade of war, half a trillion dollars, and innumerable strategies,” wrote Jessica Tuchman Mathews, the president of the Carnegie Endowment for International Peace, President Obama’s decision “brings the United States back nearly full circle to the limited ‘no boots on the ground/special forces/air power’ approach of the Bush presidency in 2002-03.”