Eleven years ago, our nation received a wake-up call. Al Qaeda terrorists flew three American airliners into the World Trade Center towers and the Pentagon. A fourth airliner headed for the White House crashed in a Pennsylvania field, thanks to the resistance of its passengers. Nearly 3,000 Americans died, billions of dollars were lost, and the nation went to war, first in Afghanistan and then in Iraq.
The attack revealed glaring security threats and vulnerabilities that demanded immediate action. Our security agencies lacked crucial information about al Qaeda -- an enemy the United States had never faced before. This enemy had no territory, no cities, no population. It did not wear uniforms or fight in conventional units. It regularly violated the most basic rule of civilized warfare by targeting civilians. We could not detect these terrorists' entry into the country or predict where they might attack next.
Any sitting president would have answered the call. But the nation was fortunate to have President George W. Bush in the Oval Office 11 years ago. Today we can take comfort in knowing that the decisions made after Sept. 11 to combat global terrorism -- including enhanced surveillance, tough interrogations and pre-emptive strikes -- kept our nation safe. Mr. Bush suffered outrageous political attacks, but he succeeded where no one thought he would. The most amazing thing to have happened to our national security in the past decade is nothing: No follow-up terrorist attack succeeded.
But what if those policies did not exist? What if a different president had answered the wake-up call? What if President Obama had been in the Oval Office 11 years ago?
First, the Obama administration would have hampered American efforts to fight terrorism by treating Sept. 11 as a criminal matter rather than an act of war. Mr. Obama has populated his administration with officials who argue that the attacks did not begin a state of war, that law enforcement rules should constrain America's response and that the courts should supervise the war on terrorism. Obama administration officials would have replaced the goal of preventing future attacks by taking pre-emptive action with the criminal law's focus on investigating and punishing suspects after the fact.
Mr. Obama campaigned for a world where terrorists get the same constitutional rights as garden-variety criminals. He wanted to end military commission trials and send terrorists to ordinary civilian trials. A terrorist would receive Miranda rights to have counsel, to remain uncooperative and to force the government at trial to reveal its vital intelligence secrets. Instead of focusing on efforts to protect our nation from a future attack, military and intelligence officials would secure "crime scenes" on battlefields, take statements from "witnesses," collect evidence in plastic baggies and secure its chain of custody for transport all the way back to the United States while they operate in a war zone.
Second, the Obama administration would not have the necessary intelligence to prevent another attack. Our only means of preventing future attacks, which could some day involve weapons of mass destruction, is to gain intelligence that permits pre-emptive action. Once attacks occur, it is too late.
Under the Obama administration, CIA interrogators would need to be polite. They would not be allowed to use coercive techniques, threats and promises or even the good-cop, bad-cop routines used in police stations every day. There would be no Guantanamo Bay detention center, no military commissions, no enhanced interrogation program, no terrorist surveillance program and hence no mosaic of intelligence to give us the information that repeatedly has identified potential attacks. That system of intelligence-gathering and analysis provided Mr. Obama with his greatest national security victory by identifying Osama bin Laden's couriers and following them to his location.
Third, the Obama administration would have undercut the executive responsibility set out by our Founding Fathers. In 2007, Mr. Obama stated, "The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation." As commander in chief and chief executive, the president has broad constitutional authority -- indeed, a duty -- to protect the nation from foreign attack.
The framers of the Constitution designed the presidency to wield power quickly and decisively. As they understood it, Congress could counter presidential decisions in foreign affairs through its powers over funding or domestic legislation. Mr. Obama ignored Congress in launching intervention in Libya, with approval by the United Nations Security Council, an international body with no standing under our Constitution to interfere with war-powers decisions.
Unlike his predecessor, Mr. Obama had years to analyze and develop the best counterterrorism approach before entering office. He criticized the policies of Mr. Bush's global war on terrorism and vowed to eliminate them. After just days in office, Mr. Obama put our nation in danger by dismantling some of our nation's most critical defenses, such as tough interrogations of al Qaeda leaders and military commission trials.
Mr. Obama's strategy courted disaster. Security lapses allowed Umar Abdulmutallab nearly to succeed in destroying Northwest Airlines Flight 253 over Detroit on Christmas Day 2009. Even Homeland Security Secretary Janet Napolitano had to retract her premature statement that "the system" had worked. In fact, it was the diligent airline passengers and crew who saved the day, not the Obama administration.
Our nation continued to succeed despite, not because of, Mr. Obama. Congress kept Guantanamo Bay open and forced the restart of military commission trials. Congress scuttled the Obama administration's plan to hold terrorist trials in civilian courts in New York City. Congress pushed to keep the courts out of running the war on terrorism as they have the regular criminal justice system. After political pressure, the demands of the real world and more experience in office, Mr. Obama realized the error of his ways and turned back to his predecessor's counterterrorism policies.
Mr. Obama expanded Mr. Bush's policies, but with a myopic twist. Mr. Obama realized the usefulness of the drone program but forgot the major drawback: Without capturing the terrorists, the United States receives no new intelligence information. Still, by not capturing the terrorists, Mr. Obama has avoided vexing detention issues by depriving terrorists of all their rights -- by killing them. In so doing, he is spending down the intelligence investments of the Bush years, gained from aggressive interrogations and electronic intercepts, without replenishing them. Perhaps, as in his economic policies, Mr. Obama has sought to purchase benefits in the political short term at the expense of the nation's long-term health. If Sept. 11 should have taught us anything, it is that the threats to our national security do not disappear for long.
John Yoo, a professor at the University of California at Berkeley School of Law, served in the Justice Department under President George W. Bush.