Says that since he took office, “there have been no large-scale attacks on the United States.” -- President Barack Obama in a speech May 23 at the National Defense University

During a major speech May 23, President Barack Obama said “there have been no large-scale attacks on the United States” since the start of his presidency.

“Now, make no mistake, our nation is still threatened by terrorists,” Obama said. “From Benghazi to Boston, we have been tragically reminded of that truth. But we have to recognize that the threat has shifted and evolved from the one that came to our shores on 9/11.”

We wondered whether he was accurate.

We see two terrorist attacks during Obama’s tenure that could be considered “large-scale.”

One is the 2009 shooting at Fort Hood, Texas, that left 13 soldiers and civilians dead and more than two dozen others wounded. Maj. Nidal Hasan, a psychiatrist in the U.S. Army Medical Corps, is the only suspect and is now awaiting a military trial.

The other incident is the bombing at the Boston Marathon on April 15 that killed three and injured more than 260. Officials are still determining the extent of the role played by Islamic extremism in the accused bombers’ motivations. (We aren’t including the Sept. 11 attack in Benghazi, Libya, because it didn’t take place on the U.S. mainland.)

The White House says Obama is accurate because neither Fort Hood nor Boston qualify as coordinated attacks on the scale of the 9/11 attacks. The White House also notes that Obama mentioned both attacks elsewhere in his speech.

Since the definition of ‘large-scale” is in the eye of the beholder, we reached out to terrorism experts for guidance. They saw two key yardsticks for determining whether an attack is “large-scale.”

Was the plot connected to a broad terrorist network?

A plot can be “large-scale” if it is logistically complicated and draws in resources from many directions.

Before the Fort Hood shootings, the government intercepted at least 18 emails between Hasan and Anwar al-Awlaki, a U.S.-born cleric tied to al-Qaida. Hasan sought out al-Awlaki for support and inspiration, but other than that, there is scant evidence that the incident was planned and carried out by an international terrorist network.

As for the Boston attack, investigators are still trying to determine how much assistance, if any, either of the suspects, the Tsarnaev brothers, may have received from other terrorists. But for now, at least, no hard evidence has emerged.

In general, then, both Hasan and the Tsarnaevs are considered more akin to “lone-wolf” terrorists who self-radicalized, rather than people who carried out a terrorist attack devised by a larger terrorist gang.

“Without the direct involvement of a more organized group and in view of other elements, they are more difficult to qualify as large-scale,” said Mathieu Deflem, a sociologist specializing in terrorism at the University of South Carolina.

How many were killed?

The attacks in Fort Hood and Boston both caused more deaths than several other terrorist attacks on U.S. soil, including a 2002 shooting at the Los Angeles airport (two killed), a 2006 vehicular attack at the University of North Carolina (injuries only) and a 2009 shooting at a U.S. Army recruiting center in Little Rock, Ark. (two killed). But they were far less than the 9/11 attacks or other major attacks of recent years.

Indeed, two school shootings not related to terrorism, at Virginia Tech (32 dead in 2007) and in Newtown, Conn. (27 dead in 2012), left more than twice as many dead as Fort Hood and about 10 times as many as were killed in Boston.

“If you use mass shootings as a baseline, then (Obama) is accurate,” said Daveed Gartenstein-Ross, a senior fellow at the Foundation for Defense of Democracies.

Benjamin Friedman, a research fellow at the libertarian Cato Institute, agreed that Obama is “on solid ground here,” adding that “it’s important to keep in mind the sort of predictions about large-scale attack that were common after 9/11. All sorts of people predicted recurring if not regular mass casualty attacks that killed many hundreds,” and that hasn’t happened.

On the other hand, the Boston bombing did result in many more injuries than either school shooting, and we think that most people would think an attack that indiscriminately injures 260 people, many with lost limbs, would qualify as “large-scale.”

Indeed, the definitions of “large-scale” are sufficiently vague that there’s a lot of room for Obama, or his critics, to either burnish or damage the administration’s record on terrorism.

There’s also a question of how much Obama can take credit — or be blamed — for the number of terrorist attacks on his watch. “Why would thwarted attacks not count?” said Ted Bromund, a senior research fellow at the conservative Heritage Foundation. “That’s like being a hockey goalie who has stopped lots of shots and then says, ‘Gee, they haven’t scored, so I guess the game must be over.’”

Our ruling

Obama said that since he has taken office, “there have been no large-scale attacks on the United States.”

Two attacks on Obama’s watch might qualify as “large-scale” — the Fort Hood shootings and the Boston Marathon bombing. They caused substantially fewer deaths than the biggest terrorist attacks of recent years, and they are believed to have been carried out by “lone wolf” attackers with limited connections to large-scale terrorist networks. But where to draw the line between small, medium and large attacks is open to interpretation. Obama’s formulation is plausible but not the only one. We rate it Half True.