President Obama’s one-year review of his strategy in Afghanistan was focused on fixing the war effort. But the review can also help the president on another front: public opinion at home.

And in that key battleground, Mr. Obama is not winning hearts and minds.

Polls show a sharp rise in the percentage of Americans who say the war in Afghanistan is not worth fighting. Instead of 40 percent opposing it a year ago when Obama took full ownership of the war, now 60 percent do. And that may rise.

This decline of support for the longest war in American history violates a key lesson from the country’s second longest war (Vietnam): The US cannot win a war without popular support; otherwise, it will need to retreat, hurting America’s reputation as well as its armed forces.

Obama did use the review for a mid-day televised pressroom briefing today to report on progress made so far and the challenges still ahead. The US appears on track to start a troop pullout in July, to finally hand off the effort to Afghan forces in 2014, and to ensure long-term US support beyond that.

New military tactics, such as night raids on homes suspected of harboring terrorists, combined with a surge of 30,000 new troops and more drone attacks on Taliban hideouts in Pakistan, have the enemy on the defensive – for now.

But the president will need to do more to bring the public on board than a rare media appearance on Afghanistan. With a near daily toll of war dead and a $100 billion-a-year price tag, the war is competing with a political surge for budget cuts and job creation.

Many Americans feel less threatened by Al Qaeda these days – as seen in the backlash against tougher airport screening. Others may be willing to risk another 9/11 attack by letting Afghanistan revert to Taliban rule. These are sentiments that a president must work against by leading a higher profile campaign to gin up support for his strategy. A 10-minute “update” by the president, as he occured today, isn’t enough.

He did warn that progress comes slowly. “There are more difficult days ahead,” he said. Any gains are fragile and reversible.

He also was stern with Pakistan’s slow efforts against terrorists – “progress does not come fast enough” – even though 140,000 Pakistani troops are now deployed along the porous Afghan border.

The president needs to travel more around the US making the case for keeping American troops in Afghanistan for another three years. Reversing the decline in popular support is essential not only to the war but to retain the 49-nation coalition that supports the US effort.

Obama has done well in retaining bipartisan support on Capitol Hill for his strategy. The Pentagon, too, helps gain public support by assisting reporters in covering both the good and bad aspects of the war. And regular public reviews of the strategy will give useful overviews for Americans in assessing the worth of their sacrifice – and reminding them of the goals.

Honesty in such assessments is essential to keep public support – another lesson from the Vietnam War. Now the president needs to kick up his role as a wartime leader and resell Americans on why a peaceful Afghanistan means peace in the US, too.