Jack Goldsmith, a former assistant attorney general in the George W. Bush administration, is a professor at Harvard Law School and a member of the Hoover Institution task force on national security and law.

“A decade of war is now ending,” President Obama proclaimed in his second inaugural address. But war is not ending, it is changing — and has been for years. Obama has cut back on heavy-footprint, conventional-force war in two countries. At the same time, he has presided over the rise of a secret, nimbler war defined by covert action, Special Forces, drone surveillance and targeting, cyberattacks and other stealthy means deployed in many countries. This new form of warfare needs a firmer political and legal foundation.

Signs of the new war are all around us. Late Monday a Justice Department “white paper” outlining the president’s power to kill U.S. citizens associated with al-Qaeda was leaked to the public. Since the beginning of the year, U.S. drone attacks in Pakistan and Yemen have killed dozens of terrorists, and the government is planning a drone base in North Africa to surveil, and perhaps later attack, Islamist militants in the region. We have also recently learned that the Pentagon is ramping up its offensive cyber-capabilities and that government lawyers have secretly concluded that the president has “broad power” to order preemptive cyberstrikes.

The administration’s primary legal basis for its global activities against al-Qaeda and affiliates is the September 2001 Authorization for Use of Military Force. But that law is a tenuous foundation for military action against newly threatening Islamist terrorist groups — including the ones causing trouble now in North Africa — that have ever-dimmer links to the rump al-Qaeda organization.

The government’s offensive cyber-activities have also grown a lot in recent years with little new legislation. U.S. Cyber Command, which coordinates such operations, was established by order of the secretary of defense. The reported cyberattacks on Iranian nuclear facilities were probably justified under the president’s self-defense powers in Article II of the Constitution and a decades-old covert-action law. In 2011 Congress tersely “affirmed” the Pentagon’s offensive cyber-operations, subject to the same legal regime that governs kinetic operations. But details of the Pentagon’s authorities in this context have been worked out in secret by the executive branch acting alone.

The administration’s secret warfare finds support in opinion polls and is almost certainly lawful. Bevies of lawyers and inspectors general monitor secret executive action, as does (in some contexts) a secret intelligence court. And the executive branch regularly reports these activities to select congressional committees that are generally supportive.

Yet the legal and political foundation for secret war is weak. The legal foundation rests mostly on laws designed for another task that government lawyers have interpreted, without public scrutiny, to meet new challenges. Outside the surveillance context, Congress as a body has not debated or approved the means or ends of secret warfare (except, perhaps, through appropriations). Because secret surveillance and targeted strikes, rather than U.S. military detention, are central to the new warfare, there are no viable plaintiffs to test the government’s authorities in court. In short, executive-branch decisions since 2001 have led the nation to a new type of war against new enemies on a new battlefield without focused national debate, deliberate congressional approval or real judicial review.

What the government needs is a new framework statute — akin to the National Security Act of 1947, or the series of intelligence reforms made after Watergate, or even the 2001 authorization of force — to define the scope of the new war, the authorities and limitations on presidential power, and forms of review of the president’s actions.

The framework statute should include a rethinking of the covert-action regime that was not designed for its current role. It should include special-operations activities within that regime. The statute should specify the means by which the president must keep the public informed about his secret wartime activities, including the legal basis for his actions. And it should have a sunset provision to force Congress to debate and renew the framework, in light of experience, after a set number of years. Whatever its contents, the proposed framework statute would be a focal point to debate and could legitimize— or not — the new type of war.

A new legal and political foundation for stealth warfare cannot succeed without the initiative and support of the president. The chances of such support, however, are dim. The Obama administration prefers to act based on old authorities and not to engage Congress in establishing new authorities for new wartime challenges. This is unfortunate for U.S. constitutional traditions and for the stability of our long-term counterterrorism strategy. And it is unfortunate for the president, not only because he increasingly acts without political cover, and because his secret wars are increasingly criticized and scrutinized abroad, but also because he alone will be bear the legacy of any negative consequences — at home and globally — of unilateral, lethal, secret warfare.