The United States is experiencing its highest level of terrorist activity since Sept. 11, 2001, according to a Heritage Foundation report published last week advocating Congress to take the U.S. terrorism threat “much more seriously.”

The report detailed the FBI’s arrest of a 19-year-old in North Carolina for conspiring with the Islamic State, the terrorist group better known as ISIS, to attack public venues in an attempt to kill hundreds of Americans.

The case is the 71st publicly known terrorist plot in the United States since 9/11.

Michael Sullivan told an undercover agent assigned to conspire with him for information that he planned the attack to support ISIS, showcasing the group’s ability to permeate borders beyond the Middle East through its extremist ideology. The report notes Sullivan’s terrorist plot as the ninth in the U.S. this year, all of which involved individuals inspired by ISIS.

The report outlines recommendations for Congress to prevent terrorist attacks. These include:

  • The continuance of government surveillance programs
  • A legal ability for local law enforcement to track terrorist activity online along with greater federal support of local and civil partners
  • Cooperation between intelligence and law enforcement among allied countries to track foreign fighters

“There is no silver bullet,” said David Inserra, author of the report and a homeland security expert The Heritage Foundation.

He said the recommendations are “critical to putting together the dots and stopping terrorists before they strike.”

“While the U.S. and others have taken steps forward on counterterrorism, we have also taken some steps back,” Inserra said. “The recent debate over the PATRIOT Act has weakened the U.S. counterterrorism capabilities and so the U.S. must rely more heavily on its other tools at just the time when it terrorist activity is spiking.”

The Heritage analysis was published soon after a State Department report found a massive increase in global terrorist attacks this past year.

The annual report published earlier this month revealed nearly 33,000 people were killed in almost 13,500 terrorist attacks in 2014. The number of attacks marked a 35 percent increase from 2013 while the death toll from these attacks jumped 81 percent.

The attacks occurred in 95 countries, but were most recurrent in Iraq, Syria, Nigeria, Afghanistan, Pakistan and India. ISIS and the Nigerian-based terrorist group, Boko Haram, were cited heavily in the report.

But the report noted that al-Qaeda’s leadership “appeared to lose momentum as the self-styled leader in the face of ISIL’s rapid expansion.”

Though the group’s leadership has weakened, the report said al-Qaeda remains the “focal point of ‘inspiration’ for a worldwide network of affiliated groups.”

The State Department cited the Syrian civil war as a significant driver of the increase in terrorism, as more than 16,000 foreign terrorists from more than 90 countries flocked to the crumbling country to fight. The majority joined ISIS, enabling the group to expand in both Syria and Iraq.

“Despite the fragmentation of al-Qaeda and its affiliates, weak or failed governance continued to provide an enabling environment for the emergence of extremist radicalism and violence,” the report said.

The scale of the attacks was also more fatal in 2014, with 20 separate attacks killing more than 100 people per attack. In 2013, only two were as deadly.

The State Department said the increase in attacks might indicate a “new era” of lone wolf terrorism in which group identity is “more fluid” and individuals carry out “self-directed” attacks to achieve a broader goal.

“You don’t have to spend much time looking at the news to see that terrorist groups are active all across the Middle East,” Inserra said. “Increased activity and military successes are certainly attracting additional fighters to their cause, whether those fighters go to the Middle East or stay at home.”