​A lot has changed in the global terrorism landscape over the past year, after ISIS lost its foothold in Iraq and Syria and security practitioners around the world continued to harden soft targets susceptible to lone wolf-style attacks.

But while the number of terrorist attacks worldwide fell in 2017, they remain historically deadly, according to new data from the University of Maryland's National Consortium for the Study of Terrorism and Responses to Terrorism Global Terrorism Database (GTD).

More than half of terrorist violence last year took place in Iraq, Afghanistan, India, and Pakistan, and almost a quarter of all deaths were in Iraq alone. And Nepal, Cameroon, Myanmar, and Kenya saw the largest increases in terrorist violence last year.

"While three consecutive years of decreases is encouraging, terrorist violence remains extraordinarily high compared to historical trends," says Dr. Erin Miller, GTD program manager. "In the decade prior to the September 11th attacks, the frequency and lethality of terrorist violence worldwide each year was less than one-third of what we saw last year."

The deadliest attack of 2017 was the truck explosion near Mogadishu, Somalia's Safari Hotel, which killed more than 580 people.

ISIS was responsible for the most attacks, but—perhaps due in part to its ongoing battle and eventual defeat in Mosul—the terrorist group was responsible for 40 percent fewer deaths than in 2016. 

In the United States, there were 65 terrorist attacks in 2017—on par with previous years—but there was a 49 percent increase in deaths, largely due to the Las Vegas shooting that killed 58 people.

Bioterrorism attacks—and how the government and infrastructure can respond—is an ongoing area of study. Several in-depth reports reveal how recent breakthroughs in science might be cause for concern for national security experts.

Michael Imperiale, a University of Michigan professor and chair of the committee that wrote a report on emerging biological threats, said the ability for bad actors to manufacture viruses or bacteria to carry out targeted attacks will soon become a reality.

"It's hard to guess when someone might try to do this," Imperiale says. "It's like a movie scenario—there's something about a biological attack that I think raises a special level of fear. It's something that might be able to spread and carry on, as opposed to someone blowing up a bomb. I think it is really something we need to pay attention to as a country, and as a world. I think the Defense Department is going to take this very seriously, and hopefully they will be able to take care of us."

The U.S. government's ability to respond to such an attack has been an ongoing point of research for the U.S. Government Accountability Office (GAO), which notes that biodefense is fragmented and faces challenges in preparing for events instead of just responding to them.

"Ultimately, we've seen a lot of different strategies come out over the years about pieces of biodefense and surveillance," says Christopher Currie, director of emergency management, national preparedness, and critical infrastructure protection at GAO.

"It's one thing to have a strategy, but you have to have the execution and implementation plan for the strategy," he explains. "Departments have to be clear about what they are supposed to be doing, and there has to be some sort of accountability, and that's a big question: Who's going to be ultimately accountable and who are the departments going to answer to in actually implementing and executing the strategy? I'm hopeful that the strategy will address that issue, because without that it's going to be difficult across such a big enterprise to implement."