It's a good thing that Mitt Romney endorsed President Obama's counterterrorism agenda. Should he win the election in two weeks, Romney will inherit an institutionalized, bureaucratic machine for using lethal robots to target and kill suspected terrorists and their allies. Killing Osama bin Laden was a one-time event; this "Disposition Matrix" is Barack Obama's real national-security legacy.

The Matrix, as detailed in a blockbuster Washington Post expose, is a master list maintained by the National Counterterrorism Center of suspected terrorists around the world, matched with methods for dealing with them. Most often, that means killing them; and most often, that means using an expanding fleet of armed drones to do so, taking off from hubs in the Arabian Peninsula, eastern Afghanistan and Djibouti's Camp Lemonnier. Despite bin Laden's death and the supposed disruption of al-Qaida's old leadership, the Matrix keeps adding names, as fast or faster than the drones drop bodies.

Maybe the White House still believes, as Obama aide Ben Rhodes recently contended, that the Arab Spring will "undercut the al-Qaida narrative." But the constellation of U.S. counterterrorism agencies is settling in for the long haul: a war that expands worldwide and shows no sign of ending. "We're not going to wind up in 10 years in a world of everybody holding hands and saying, 'We love America,'" one tells the Post's Greg Miller.

There's a rhetorical consensus in Washington that, as Romney said at Monday's debate, the U.S. "can't kill our way out of this mess." It's spoken so often it's a cliche. But in practice, killing appears to be the mainstay of U.S. efforts: nearly 3,000 people have been slain by drone strikes, according to a Post online database, including an undisclosed number of civilians. And the security agencies are preparing for even more.

As the Post's Greg Miller recounts, the security bureaucracy has dug in. The Joint Special Operations Command (JSOC), the elite military organization that killed bin Laden, now runs a targeting center outside Washington. The CIA, Miller writes, seeks to expand its drone fleet and remain "a paramilitary force," rather than "return to its pre-Sept. 11 focus on gathering intelligence." The U.S. military might be drawing down from Afghanistan, but JSOC and the CIA are what backstop that retrenchment.

At the nearby National Counterterrorism Center, teams of analysts and officials compile the targeting lists compiled by JSOC and the CIA, and match them to unspecified standards for dealing with terror suspects. They review the Disposition Matrix every three months before passing it along to the White House for approval of specific actions outside the well-entrenched Pakistan drone campaign. There, John Brennan, Obama's trusted chief counterterrorism deputy, runs an interagency meeting that passes selected targets for killing to Obama for approval.

The Matrix is a "work in progress," officials told Miller, and goes beyond drone strikes to include "sealed indictments and clandestine operations." (It's not clear what grand juries are issuing such indictments.) But if the Matrix actually contains names of terror suspects, then it may not be exhaustive of U.S. counterterrorism efforts: The CIA also conducts so-called "signature strikes" against unknown persons who merely match a demographic profile for terrorism.

What's more, there are constraints on the U.S.' ability to take non-lethal action against terrorists, some of them self-imposed. Protracted disagreements between the White House and Congress over terrorism detentions, for instance, have led to few terrorism suspects being captured outside Afghanistan. Those who have, like the Somali suspect Ahmed Abdulkadir Warsame, have been placed in ad hoc prisons like the brig of the USS Boxer. There are some signs Congress might revisit the detentions question, but until some resolution exists, lethal strikes will remain the option of choice.

And there's little evidence of a strategy, like the one Romney called for on Monday, in which the lethal operations fit. After 10 years and two presidencies, the U.S. still lacks a mature strategy for stemming the demand for al-Qaida globally. What it's got instead is "Countering Violent Extremism," a jumble of efforts, many outside government, that either borrow the tactics of anti-gang task forces or send Muslim rappers on pro-U.S. goodwill tours.

Obama did not run for president to preside over the codification of a global war fought in secret. But that's his legacy. Administration officials embraced drone strikes because they viewed them as an acceptable alternative to conventional ground warfare, which it considered too costly and too public, but the tactic has now become practically the entire strategy. Micah Zenko at the Council on Foreign Relations writes that Obama's predecessors in the Bush administration "were actually much more conscious and thoughtful about the long-term implications of targeted killings," because they feared the political consequences that might come when the U.S. embraces something at least superficially similar to assassination. Whomever follows Obama in the Oval Office can thank him for proving those consequences don't meaningfully exist – as he or she reviews the backlog of names on the Disposition Matrix.