The United States now enters its tenth year of war in Afghanistan, longer than U.S. involvement in World War I and World War II combined. The cost to U.S. taxpayers is $120 billion a year, at a time when the country has deep needs at home.

The U.S. troop presence in Afghanistan has gone from 5,000 in the year after the October 2001 ouster of the Taliban to 37,000 when President Barack Obama came into office in January 2009. He has steadily increased the U.S. presence and today roughly 100,000 U.S. troops are in Afghanistan.

Now, as we come to the latest strategic review, it is abundantly clear that the president and his team have done little to rethink the U.S. military presence in Afghanistan. He plans to start withdrawing troops in July, with pullout by December 2014. More of the same.

His review did say that in 2011 “we will intensify our regional diplomacy to enable a political process to promote peace and stability in Afghanistan.” That’s the right approach, but it is vague and comes almost as an afterthought.

And the untimely death last week of Richard Holbrooke, the U.S. special representative to Afghanistan and Pakistan who was the strongest and most skilled advocate of that approach, makes that essential task all the more daunting.

Holbrooke, who brokered the Dayton accords that ended the Bosnia conflict, understood the vital importance of diplomacy in ending conflicts. As Joel Klein of Time magazine writes, Holbrooke understood that “equilibrium could only be reached in Afghanistan if the Pakistanis and Indians established better relations, and stopped seeing Afghanistan as a strategic prize.”

The rivalry between Pakistan and India is driving much of the instability in Afghanistan and creating a vacuum for al-Qaida and other extremists to exploit.

Work on a regional bargain that includes India and Pakistan is necessary because an indefinite U.S. military presence in Afghanistan is unsustainable and fuels the insurgency, which is fighting not for the Taliban but against the presence of foreign soldiers and a corrupt government in Kabul.

The United States has had, and will continue to have, a strong air and naval presence in the Persian Gulf and Indian Ocean. Those forces are well positioned to attack terrorist camps without being an occupying force on the ground.

Obama continues to promise a phase-down of U.S. troops in Afghanistan, starting in July, a good thing. But he’s got to get a real regional diplomatic strategy moving, too. The current course does not serve U.S. interests in the region or at home.