WASHINGTON (Reuters) – The U.S. Justice Department is considering legal changes to combat what it sees as a rising threat from domestic anti-government extremists, senior officials told Reuters, even as it steps up efforts to stop Islamic State-inspired attacks at home.

Extremist groups motivated by a range of U.S.-born philosophies present a “clear and present danger,” John Carlin, the Justice Department’s chief of national security, told Reuters in an interview. “Based on recent reports and the cases we are seeing, it seems like we’re in a heightened environment.”

Over the past year, the Justice Department has brought charges against domestic extremist suspects accused of attempting to bomb U.S. military bases, kill police officers and fire bomb a school and other buildings in a predominantly Muslim town in New York state.

But federal prosecutors tackling domestic extremists still lack an important legal tool they have used extensively in dozens of prosecutions against Islamic State-inspired suspects: a law that prohibits supporting designated terrorist groups.

Carlin and other Justice Department officials declined to say if they would ask Congress for a comparable domestic extremist statute, or comment on what other changes they might pursue to toughen the fight against anti-government extremists.

The U.S. State Department designates international terrorist organizations to which it is illegal to provide “material support.” No domestic groups have that designation, helping to create a disparity in charges faced by international extremist suspects compared to domestic ones.

A Reuters analysis of more than 100 federal cases found that domestic terrorism suspects collectively have faced less severe charges than those accused of acting on behalf of Islamic State since prosecutors began targeting that group in early 2014.

Over the past two years, 27 defendants have been charged with plotting or inciting attacks within the United States in the name of Islamic State. They have faced charges that carried a median prison sentence of 53 years – half of the defendants faced more, and half faced less.

In the same period, 27 adherents of U.S.-based anti-government ideologies have been charged with similar activity. They faced charges that carried a median prison sentence of 20 years.

Carlin said his counter-terrorism team, including a recently hired counsel, is taking a “thoughtful look at the nature and scope of the domestic terrorism threat” and helping to analyze “potential legal improvements and enhancements to better combat those threats.”

The counsel, who was appointed last October and has not been named publicly, will identify cases being prosecuted at the state level that “could arguably meet the federal definition of domestic terrorism,” a Justice Department official said.

That would give the department a direct role in more domestic extremism cases.

Recognizing that domestic threats were “rapidly evolving, and had the potential to grow,” the department in March 2015 rated disrupting such terrorists as a key component of its broader counter-terrorism efforts, officials said.

THE THREAT PENDULUM

The Justice Department aggressively pursued domestic extremists after Timothy McVeigh bombed a federal building in Oklahoma City in 1995, killing 168 people.

The government shifted its focus to international terrorism after al Qaeda killed nearly 3,000 Americans on Sept. 11, 2001.

But in recent years anti-government activists, like those who occupied a wildlife preserve in eastern Oregon last month, have regained prominence.

As law enforcement experts confront domestic militia groups, “sovereign citizens” who do not recognize government authority, and other anti-government extremists, they also face a heightened threat from Islamic extremists like the couple who carried out the Dec. 2 shootings in San Bernardino, California.

“A new development we’re seeing is that when it comes to ISIL investigations, the flash-to-bang time from radicalization to action appears to be happening faster than with other types of terrorists,” said Michael Steinbach, the head of the FBI’s Counterterrorism Division.

As a result, government agents are quick to investigate people who appear sympathetic toward Islamic State, current and former officials say. But some say the government has been overzealous in its pursuit of Islamic State suspects.

Similar actions by extremist suspects have yielded sharply disparate sentences.

Eight Islamic State-related defendants have been sentenced so far, to prison terms that range from three to 20 years, the Reuters review found. Over the same period, 18 domestic extremists have been sentenced to terms from one day to 12 years.

Prosecutors say Harlem Suarez, 23, of Key West, Florida, tried to buy a bomb last year from an undercover FBI agent as he plotted attacks on behalf of Islamic State. He faces a possible sentence of life in prison and has pleaded not guilty.

Michael Sibley, 67, left two unexploded pipe bombs and a Koran in a park in Roswell, Georgia in 2014 in what he later told police was an attempt to highlight the danger of Islamic terrorism. He pleaded guilty and faces a maximum of five years in prison.

“A different standard is being applied to Muslims than to other people,” said Daryl Johnson, a former counterterrorism expert at the Department of Homeland Security who now works as a law enforcement consultant.

“SPRING-LOADED”

Steinbach said that the FBI can never open up any type of investigation “just on the basis of race, creed, or religion,”

But he added that federal agents are “spring-loaded” to open investigations into Americans who support groups on the State Department list of designated terrorist organizations.

The maximum penalty for supporting one of these groups has been raised from 10 years to 20 years in prison since 2001.

It has been applied in 58 of the government’s 79 Islamic State cases since 2014 against defendants who engaged in a wide range of activity, from traveling to Syria to fight alongside Islamic State to raising money for a friend who wished to do so.

Judges usually issue sentences below the maximum, but some charges trigger sentencing “enhancements” that raise the baseline sentence a judge can issue – and the material support charge raises it more than most.

Domestic groups enjoy greater constitutional protections because being a member of those groups, no matter how extreme their rhetoric, is not a crime.

Prosecutors can bring “material support” terrorism charges against defendants who aren’t linked to groups on the State Department’s list, but they have only done so twice against non-jihadist suspects since the law was enacted in 1994. The law, which prohibits supporting people who have been deemed to be terrorists by their actions, carries a maximum sentence of 15 years in prison.

Current and former federal prosecutors say they rarely consider that statute in domestic terrorism cases because it is often hard to convince a jury that someone who is not affiliated with a foreign group can be guilty of terrorism.

William Wilmoth, a former federal prosecutor who invoked that law in a 1996 case against a West Virginia militia member, said he was surprised to hear that it isn’t used more often.

“These guys have every right to have off-center political views,” he said. “But when they made affirmative steps to blow up an actual federal facility… we thought it was an important place for us to go and prosecute.”

(Reporting by Julia Harte, Julia Edwards and Andy Sullivan; editing by Stuart Grudgings)