In President Barack Obama's twin narratives, the United States is both leaving Afghanistan and staying there.

The different messages are meant for different audiences, one at home and one away. As Obama's brief, symbolic visit to Afghanistan on Wednesday made clear, the more important audience is American voters fed up with a war that will be in its 12th year on Election Day this fall.

The president flew in secret to sign a long-awaited security compact with Afghanistan. It was after midnight in Kabul when the signing took place, and 4 a.m. there when Obama addressed Americans in a specially arranged 7:30 p.m. EDT speech on network television. By the time most Afghans woke up, Obama was gone.

"My fellow Americans," Obama said from Bagram Air Field, "we have traveled through more than a decade under the dark cloud of war. Yet here, in the predawn darkness of Afghanistan, we can see the light of a new day on the horizon."

The backdrop of armored troop carriers matched Obama's message of praise for US forces who fought and died in Afghanistan, but it was an odd fit for what followed — a direct appeal to American optimism and self-interest in an election year.

"As we emerge from a decade of conflict abroad and economic crisis at home, it is time to renew America," Obama said.

The agreement pledges ongoing US support for Afghanistan after 88,000 US combat forces leave. The pact envisions wide-ranging US involvement in Afghan economic and security affairs for a decade, if only as an adviser or underwriter. It gives Afghans a promise of more roads and schools and support for the uneven Afghan fighting forces.

It gives the US a security foothold in the country to bolster Afghan forces for their continued fight against Taliban-led militants or al-Qaida, and to keep an eye on neighboring Iran. Obama's emphasis on a long-term US commitment to Afghanistan reflects a lingering worry about the threat of a Taliban resurgence after 2014, when US and NATO combat forces are scheduled to leave.

With the agreement signed Tuesday, the US also has in mind the strategic significance of preserving a military partnership on Iran's eastern frontier, even if it does not include permanent US bases.

Even after the US combat mission is concluded in 2014, it is likely that thousands of US troops will remain for some years to conduct counterterrorism strikes and otherwise train and advise Afghan forces, and help the Afghans collect and exploit intelligence on insurgents and other military targets.