Navy SEALS killed Osama bin Laden in May 2011, avenging his mass-murdering attacks on America. And President Barack Obama, who ordered that daring raid, understandably found a way to mention “how we went after al-Qaida and bin laden” during Wednesday night’s domestic-issues debate in Denver.

But in the 17 months since bin Laden’s overdue demise, his al-Qaida terror organization has been stubbornly “fighting back,” as one of the nation’s leading experts on terrorism puts it, and is now “thriving in the Arab world.”

Bruce Reidel, who served Presidents George W. Bush and Barack Obama as a senior adviser on terrorism, wrote in a recent Brookings Institution column that al-Qaida has made new gains in Yemen, Iraq, Syria, the Egyptian Sinai and Africa, and that its main allies in Pakistan, including the Taliban, “continue to enjoy the patronage of the Pakistani intelligence services.”

Among other steps, al-Aqaida has seized what Mr. Reidel calls “a new stronghold in Africa,” the control of a large area of northern Mali where it has begun training terrorists from Algeria, Morocco, Nigeria and other African states.

Mr. Reidel sounded that alarm before armed terrorists killed the American ambassador to Libya and radical Islamic activists provoked crowds to break into the grounds of the U.S. Embassy in Cairo. Al-Qaida has claimed responsibility for the outrage in Libya.

Mr. Reidel noted that al-Qaida still looks for opportunities to attack the U.S. and Western Europe, and recently sent terrorists from Chechnya to attack Gibraltar, a plot frustrated by the Spanish government.

While the administration has downplayed the idea that this nation is at “war” with Islamic radicals, those enemies remain belligerent. They have been at open war with the U.S. at least since the first World Trade Center bombing in February 1993. Or you could trace the start of this war to Ayatollah Ruhollah Khomeini’s seizure of power in Iran — and Islamic radicals seizure of the U.S. Embassy in Tehran — in 1979.

The failure to protect Amb. Christopher Stevens in Libya, despite warnings, was a serious failure for America and a grisly victory for al-Qaida.

Meanwhile, the Obama administration’s strategy in Afghanistan is faltering for a complex variety reasons — including the Taliban’s alliance with al-Qaida.

On the plus side, local officials in Yemen told CNN on Thursday that U.S. drone strikes killed five suspected al-Qaida fighters in Yemen.

Clearly, America’s conflict with al-Qaida — in other words, with Islamic radical terror — continues. While killing bin Laden was a grand achievement, it hasn’t ended the al-Qaida menace.