With his new comprehensive plan for Afghanistan and Pakistan, President Obama has asserted leadership over the war that matters most to America’s security - the one against Al Qaeda and the Taliban.

We do not underestimate the difficulty of succeeding against these deadly adversaries. But it was greatly encouraging simply to see the president actually focusing on this war and placing it in the broader regional framework that has been missing from American policy. That is a good first step toward fixing the dangerous situation that former President George W.Bush created when he abandoned the necessary war in Afghanistan for the ill-conceived war of choice in Iraq.

Mr.Obama has come back to first principles. Instead of Mr.Bush’s vague talk of representative democracy in Afghanistan, he defined a more specific mission.“We are not in Afghanistan to control that country or dictate its future,”Mr.Obama said, but“to disrupt, dismantle and defeat Al Qaeda in Pakistan and Afghanistan.”

The United States removed the Taliban from power in Afghanistan in 2001 as it sought to stamp out the Al Qaeda militants behind the 9/11 attacks. More than seven years later, the Taliban and Al Qaeda are stronger than ever. Militants have crossed the border into Pakistan, where they plot attacks against the United States, its allies and Pakistan.

To rebuild popular support for a mission that once was a global priority, Mr.Obama and other leaders have to keep repeating this message: If Afghanistan falls, if Pakistan falls, extremists will unleash even more fury. That is a threat to us all. Mr.Obama’s plan breaks welcome new ground by treating Afghanistan and Pakistan as a single coherent theater of operation. It finally sets benchmarks for measuring progress by Kabul and Islamabad. It seeks to bring other regional players into the discussion, including Iran and Russia.

The new plan also recognizes there is no military-only solution. We are encouraged by Mr.Obama’s plans to send hundreds of civilians to help develop new jobs in Afghanistan and an economy not tied to poppy production. Like him, we strongly endorse a bipartisan Congressional proposal to invest $1.5 billion annually in Pakistan’s people with the building of schools, hospitals and roads. America cannot hope to defeat the insurgents if Afghans and Pakistanis don’t see their lives improve.

Mr.Obama confronts many challenges. He must persuade the Pakistani intelligence service to stop underwriting the Taliban and the Afghan government to eradicate corruption. He also must persuade NATO to contribute more to the war effort - if not combat troops in Afghanistan, then trainers or development aid.

His plans to urge so-called moderate Taliban to abandon their hard-line leaders is worth trying. But that will require dealing with one of the most disturbing bits of recent news. Seven years into the fight, the leader of the American intelligence community acknowledged that it knows shockingly little about the Taliban command structure.