The enemy that attacked the US on 9/11 is today rapidly regaining its strength

On the campaign trail in the fall of 2012, President Barack Obama trundled up to a podium and declared that al-Qaeda had been "decimated." The following day, he pronounced that the terrorist group was "on the path to defeat." Even at the time, those statements smacked of hubris, but now we know they were also dead wrong.

During Obama's presidency, al-Qaeda began a resurgence that has left it today with arguably more power than it has had since America invaded Afghanistan in 2001. They've accomplished this by eschewing gory attacks in favor of empowering their affiliates and building relations with local communities-all while maintaining their determination to attack the west. With the Islamic State fading, al-Qaeda now stands as the heir to ISIS's jihadist ideology. Yet it's also shrewder and better prepared than its hyper-violent brethren ever were.

Let's start in Afghanistan, subject of a recent speech by President Trump, who promised that victory there will mean "obliterating ISIS" and "crushing al-Qaeda." It is the latter that will occupy most of his attention. The familiar old alliance between al-Qaeda and the Taliban has reappeared, and its forces have either seized or contested 40 percent of the country. That is an astonishing rebuke to past presidents: After 16 years of war and more than $800 billion in funding, Afghanistan is still threatened by Taliban rule. Matters have been made worse by neighboring Pakistan, which the Taliban is also working to destabilize, turning this into a cross-border conflict.

In Yemen, a long and sanguinary bombing campaign by an Arab coalition led by Saudi Arabia has left people starving and beleaguered, and al-Qaeda has stepped in to provide protection and stability. Al-Qaeda in the Arabian Peninsula (AQAP), regarded by experts as the franchise most determined to attack the U.S. homeland, has "emerged arguably as the biggest winners of the failed political transition and civil war that followed," according to the International Crisis Group. Yemeni suffering, the power vacuum ripped open by the conflict, and the Saudis' predictably kid-gloves approach to Sunni terrorists, have elevated AQAP from the struggling jihad club that it was five years ago to a major political player today.

But perhaps nowhere are al-Qaeda's gains more alarming than in Syria. The al-Qaeda franchise there is neither al-Qaeda nor a franchise: it goes by the name Tahrir al-Sham, after the al-Qaeda affiliate Jabhat al-Nusra severed ties from its parent group and merged with several other extremist militias. But it has continued al-Qaeda's double act of solidifying support in local communities-by establishing relief departments, for example, and running food convoys-while gradually implementing Sharia Law. Tahrir al-Sham, née al-Nusra, has long been the most powerful and best-equipped faction of the Syrian rebellion. In July it won control of the key city of Idlib.

It's a sobering reality: The enemy that attacked us on 9/11 is today rapidly regaining its strength. The problem is not that we have overstepped by attacking al-Qaeda; it is that we have allowed ourselves to become sidetracked by diversions, like Iraq's Saddam Hussein and Libya's Moammar Gaddafi, both of whose countries became havens for terrorists after we deposed them. Likewise in Yemen, we've backed the Saudi-led campaign against the Houthi rebels, only for al-Qaeda to end up the beneficiary, while in Syria our opposition to Bashar al-Assad has helped empower Tahrir al-Sham. And in Afghanistan we've been focused on other threats, too.

America's allies also are not shouldering their share of this burden. There is one nation in particular that has shirked its load, whose malign involvement lurks as a common denominator under every one of those aforementioned countries: Saudi Arabia. The royals in Riyadh have funded extremist schools and mosques in Afghanistan and Pakistan, and Saudi donors are bankrolling the Taliban to this day. Saudi Arabia's blundering airstrikes have triggered the al-Qaeda backlash in Yemen. And for years now, the Saudis have recklessly armed the jihadist factions of the Syrian rebellion.

They've done all this while cunningly nurturing an alliance with the United States. President Trump could call up Riyadh tomorrow and demand corrective action. Instead, he spent his first Middle East trip touching their weird orb while taking his eye off the al-Qaeda ball. It is a mistake he needs to correct if he is to be serious about stamping out terrorism.

Matt Purple is a fellow at Defense Priorities and editor of Rare Politics.

This column does not necessarily reflect the opinion of Business Insider.