The national security threats against the United States have changed dramatically even in the past two years, according to senior Trump administration officials.

Whereas homeland security and federal investigators used to focus on fighting terrorism abroad, FBI and Department of Homeland Security leaders told the Senate Wednesday that the fight has come home because the threats are now stateside as well as in cyberspace.

The top five areas of concern that keep senior officials awake at night fall into the categories of critical infrastructure, cybersecurity, terrorism, border security, and drones. China, Iran, North Korea, and Russia are the countries with both the intent and capability to attack the U.S. in cyberspace.

"After 9/11, our strategy was to take the fight to enemies abroad so we did not have to fight them here at home," DHS Sec. Kirstjen Nielsen told the Senate Homeland Security and Governmental Affairs Committee. "Unfortunately, that is no longer the world we live in. Our enemies do not respect borders are not constrained by geography. Today’s threats exist in a borderless — and increasingly digital — world."

Today, the federal government’s biggest concerns are attacks on critical infrastructure, hacks into America’s private and public cyberspaces, and gaps in America’s physical borders. The issue of foreign and domestic terrorist attacks remain significant but a growing threat is the use of drones to surveil law enforcement and smuggle contraband.

Terrorists and nation-states could attack the U.S. through its critical infrastructure: banks, energy, telecommunications, and other industries. By disabling America’s power grid or shutting down financial institutions, business would be suspended and communication networks shut down.

The risk is one of the most severe types DHS faces. At the center of this type of attack are foreign states, Nielsen said, listing China, Iran, North Korea, and Russia.

Election infrastructure is a major concern for the government in light of next month’s midterm elections. More than 10,000 state and local jurisdictions make up the country’s election infrastructure. Because there is no one set method of voting and counting ballots, it makes it harder for a perpetrator to affect all elections, but it also makes it more challenging for DHS — who is tasked with helping localities secure their operations — to provide such a variety of resources.

FBI Director Christopher Wray said cybersecurity goes hand in hand with the well-being of critical infrastructure.

“Virtually every national security and criminal threat the FBI faces is cyber-based or technologically facilitated. We face sophisticated cyberthreats from foreign intelligence agencies, hackers for hire, organized crime syndicates, and terrorists,” Wray said, according to his prepared remarks. “They seek to strike our critical infrastructure and to harm our economy.”

The most malicious cyber actions are being carried out by state-sponsored hackers and global organized crime networks.

“Cyberattacks now exceed the risk of physical attacks,” Nielsen said. “Don’t get me wrong: terrorists, criminals, and foreign adversaries continue to threaten the physical security of our people, but cyberspace is the most active battlefield, and it extends into almost every American home.”

In 2017, hundreds of thousands of computers in more than 150 countries were infected with the WannaCry ransomware virus. The U.S. identified North Korea as the culprit behind the attack, which hurt healthcare and telecommunications industries.

DHS component, the National Cybersecurity Protection System, only detects a single-digit percentage of cyberattacks against the government and private entities. From January 2016 through April 2017, it only knew about 1,600 of the more than 44,000 incidents. From April of last year through September of this year, the office detected 379 of the more than 39,000 attacks.

Terrorist groups are increasingly using cyberspace to recruit personnel and money to grow their operations.

“The FBI assesses HVEs [home-grown violent extremists] are the greatest terrorism threat to the homeland. These individuals are global jihad-inspired individuals who are in the U.S., have been radicalized primarily in the U.S., and are not receiving individualized direction from FTOs [foreign terrorist organizations],” Wray said, according to his remarks.

But terrorist groups overseas also remain a serious concern. Despite major losses of territory, the Islamic State is still motivated to gain new ground and continue recruiting people. Wray said the group’s unique message has helped it continue to attract new recruits.

“Unlike other groups, ISIS has constructed a narrative that touches on all facets of life, from family life to providing career opportunities to creating a sense of community,” he said.

Despite the Islamic State’s loss of holdings in Iraq and Syria, it has grown on a global level, making it a continued challenge for the government to track.

To date this calendar year, the U.S. has seen three official terrorist attacks compared to five last year.

National Counterterrorism Center acting Director Russell Travers said al Qaeda still wants to carry out a massive attack on the U.S. homeland and emerging groups like the Lebanese Hezbollah and Islamic Revolutionary Guard Corps-Qods Force in Iran are also making a name for themselves internationally and pose a threat to America.

Wray said terrorists overseas are using and will continue to rely on drones, unmanned aerial systems, to surveil government forces, smuggle contraband, and carry out attacks against U.S. allies. Groups specifically using these flying machines are transnational criminal organizations.

“While there has been no successful malicious use of UAS by terrorists in the United States to date, terrorist groups could easily export their battlefield experiences to use weaponized UAS outside the conflict zone,” said Wray, according to a statement submitted for the record. “We have seen repeated and dedicated efforts to use UAS as weapons, not only by terrorist organizations, such as ISIS and al Qaeda, but also by transnational criminal organizations such as MS-13 and Mexican drug cartels, which may encourage use of this technique in the U.S. to conduct attacks.”

Senate Homeland Security and Governmental Affairs Chairman Ron Johnson admitted to witnesses at the start of the hearing that he did not believe U.S. borders were even secure in addition to the growing list of other concerns.

“Unfortunately, I have to say our border is not secure. Not even close,” said the Wisconsin Republican.

Johnson said his worry is that a terrorist will be able to sneak over America’s northern or southern border and be able to carry out a domestic attack.

In addition, U.S. Customs and Border Protection Commissioner Kevin McAleenan said earlier this year that transnational smugglers are using people they traffic from Central America and elsewhere to the border in order to overwhelm Border Patrol and run drugs and other contraband in less-guarded areas.

Johnson said “loopholes” or legal decisions that require families and kids be released from federal custody once apprehended gives traffickers a way to lure people into paying thousands of dollars to be transported to the U.S.