As Americans try to make sense of the tragic shooting in Aurora, Colo., it is natural to reflect on other similar incidents that have scarred our collective memory. And in recent days, this massacre has been compared to shootings at Columbine, Virginia Tech, Tucson, the Holocaust Memorial and Fort Hood.

The problem? One of these incidents is not like the others. The Aurora shooting was a senseless act of violence; Fort Hood was a terrorist attack.

The Post quoted a forensic psychiatrist who declared that the shooters in all these cases had a “common motive.” No, Army Maj. Nidal Hasan’s motive was different from that of James Holmes or Seung-Hui Cho. Hasan’s was the same motive that led 19 evil men to fly airplanes into the Pentagon and the World Trade Center on Sept. 11, 2001: He wanted to wage jihad against the United States.

One day before the Aurora shootings, former FBI and CIA director William Webster released a 173-page report on the tragic failure to prevent the Fort Hood attack. It included declassified details of e-mail messages between Hasan and Anwar al-Awlaki, the leader of al-Qaeda in the Arabian Peninsula who was killed last year in a U.S. drone strike. In one e-mail, Hasan asks Awlaki whether he considered Muslims who join the U.S. armed forces and “kill other us soldiers in the name of Islam … with the goal of helping Muslims/Islam (Lets just assume this for now) fighting Jihad and if they did die would you consider them shaheeds” (martyrs).

In another e-mail, Hasan asks Awlaki about “the issue of ‘collateral damage’ where a decision is made to allow the killing of innocents for a valuable target.” The FBI intercepted these and other troubling e-mails but concluded that they posed no serious danger and that an investigation was not necessary.

On Nov. 5, 2009, Hasan entered the Fort Hood deployment center, jumped on a desk and yelled “Allahu Akbar!” as he shot and killed 13 people and wounded 43 others. Soon after the Fort Hood attack, Awlaki stated that while he neither ordered nor pressured Hasan to harm Americans, “I blessed the act because it was against a military target. And the soldiers who were killed were not normal soldiers, but those who were trained and prepared to go to Afghanistan and Iraq.”

Awlaki praised Hasan as a “hero” and declared: “Fighting against the U.S. army is an Islamic duty today. The only way a Muslim could Islamically justify serving as a soldier in the U.S. army is if his intention is to follow the footsteps of men like Nidal.”

When authorities searched Hasan’s home after the attacks, they found business cards that omitted his U.S. military rank but included a cryptic abbreviation, “SoA” — apparently “Soldier of Allah” or “Servant of Allah.”

Hasan was more than a deranged killer; he was a home-grown al-Qaeda terrorist. Yet from the beginning, the Obama administration sought to play down Hasan’s ties to terror. Soon after the shootings, Obama speculated that the attack was the result of an overtaxed military, declaring “everybody understands how outstanding the young men and women in uniform are under the most severe stress. There are going to be instances in which an individual cracks.” And in his memorial speech at Fort Hood, Obama refused to call the killings a terrorist act and declared it was “hard to comprehend the twisted logic that led to this tragedy.”

Hasan’s logic is not hard to comprehend at all. He followed a clear and focused ideology — Islamic radicalism — that is evil but not insane. He studied this ideology, and he committed mass murder in its name. He conspired with an enemy commander — and then killed to advance the enemy’s vision and objectives.

The men and women who lost their lives in Aurora Friday were killed because they were in the wrong place at the wrong time. The men and women who lost their lives at Fort Hood were killed because they wore the uniform of the United States of America. This means the Fort Hood massacre belongs not with Aurora, Columbine, Virginia Tech and Tucson in the pantheon of tragic and senseless killings. It belongs in the pantheon of terrorist attacks against the United States — alongside the bombings of the U.S. embassies in East Africa, the destruction of the USS Cole, the attempted bombings of a commercial airliner over Detroit and an SUV in Times Square, and — yes — the attacks of Sept. 11, 2001.

Sens. Joe Lieberman (I-Conn.) and John Cornyn (R-Tex.) and Rep. Peter King (R-N.Y.) have introduced bipartisan legislation to award Purple Hearts to those killed and wounded at Fort Hood — just as Purple Hearts were awarded to the military victims of 9/11. Aurora was a horrific crime, and the victims deserve our prayers. But those who perished at Fort Hood deserve something more as well — the recognition that they gave their lives in service to our country.