In testimony before the Senate Armed Services Committee yesterday, head of U.S. Central Command Gen. David H. Petraeus disclosed that American commanders have requested the deployment of an additional 10,000 U.S. troops to Afghanistan next year, but he said the request awaits a final decision by President Obama this fall.

Sen. John McCain (R-AZ) moved to question why President Barack Obama did not reveal this when he unveiled his Afghanistan strategy this past weekend: “To dribble out these decisions, I think, can create the impression of incrementalism,” he said.

“Incrementalism” is exactly what we cannot afford. Heritage analyst James Carafano explains why:

America’s most notable half-measure war was Vietnam, led by Gen. William Westmoreland. President Lyndon Baines Johnson took on the war so no one could call him “soft on Communism.” But he was more interested in with pumping money into an ambitious domestic agenda.

His solution: an “incremental” strategy for the war. He would give the Pentagon the bare minimum in forces and commitment that still might convince the North Vietnamese to throw in the towel. To further keep costs down, Johnson forced the Joint Chiefs to raid other parts of the defense budget to help pay for the war.

Unfortunately, an incremental strategy gives a determined and resourceful foe the time and space to adjust. North Vietnam adjusted—pulling back into sanctuaries in the north when pushed by U.S. forces and drawing heavily on support from Communist allies.

The war steadily escalated—increasing both our military commitments and Johnson’s political investment in the conflict. Half-hearted and increasingly costly is no way to fight a war. Johnson’s popularity plummeted to the point that he didn’t even try to win re-election.