For the past 20 years, U.S. special operators have been on the frontline of the struggle against terrorism.

Those special operators are small in number compared with their conventional counterparts, but they’ve made an outsize contribution to the global war on terrorism.

After the invasions of Afghanistan and Iraq, most U.S. counterterrorism operations involved unconventional warfare, with commandoes training local partners and conducting raids.

That has played to the strengths of special operators, who see themselves as a scalpel rather than a hammer. Special operations forces have thrived in such fast-paced, ambiguous environments.

First in, Last out

In the wake of the September 11 terrorist attacks, special operators were the first in Afghanistan.

The Army’s elite Delta Force launched a daring operation to take out Mullah Omar, the leader of the Taliban, in his own headquarters deep in enemy territory. While that was taking place, Green Berets were leading local anti-Taliban fighters to defeat the Taliban and Al Qaeda in a matter of weeks.

When the insurgency threatened to destroy Iraq and foil U.S.-led reconstruction efforts there, special operation forces orchestrated an industrial-scale counterterrorism campaign. Tier 1 units — Delta Force and SEAL Team Six, now known as Naval Special Warfare Development Group — led the effort to dismantle Al Qaeda in Iraq with a relentless campaign of raids, sometimes as many as three at night.

The 75th Ranger Regiment also took on a more significant role, going after high-value targets that in the past would’ve been assigned to the Tier 1 units.

Green Berets trained the Iraqi counterterrorism unit that later led the brutal but effective fight against ISIS. In Afghanistan, Green Berets trained their Afghan counterparts, aiming to win the hearts and minds of the population and secure their communities.

Navy SEALs, Marine Raiders, Reconnaissance Marines, and Air Commandos played equally important roles in taking down terrorists or enabling other special operations.

“No one can deny that this has been an extremely tough war. Perhaps not in the sense that military historians think and write about warfare from the ancient times to today. This was our war. [Special-operations forces] were at the tip of the spear, and we fought relentlessly,” a retired Delta Force operator told Insider.

“That is not to ignore or diminish the contribution of our conventional brothers and sisters,” the retired operator added. “They played a hugely important role, and we are immensely grateful for their contribution. It is one of the SOF truths: Special operations require non-SOF support. I want to stress this. It’s always a jointed or combined effort.”

The retired Delta operator and others in this story spoke anonymously to describe operations they conducted while in uniform.

Small numbers of U.S. special operators remain in Iraq, but U.S. forces have withdrawn from Afghanistan, and the shift toward competition with near-peer adversaries like Russia and China means the war on terror is likely to continue winding down.

A Heavy Toll

In two decades of fighting terrorism, 660 special operators have been killed and 2,738 wounded. Those totals are small compared to the casualties in past wars, but they took a significant toll on those forces.

There are about 70,000 special operators across all services, making them about 3.5% of the U.S. military’s 2.1 million total troops. In such a small community, where members know each other by name, face, or reputation, every casualty is felt deeply.

“We played a big part in the war” and suffered because of it, with members of some units deploying more than a dozen times, straining families and mental health, a former Green Beret told Insider.

“Broken marriages [and] missed birthdays and anniversaries are just some of the residues of the relentless deployment cycle,” the former Green Beret said. “But we were defending America forward. We weren’t forced or coerced. We are volunteers. We responded [to] the cowardly attacks [of 9/11], and we responded with force and precision.”

While that toll has been heavy, U.S. special operations forces are now better prepared to face those near-peer adversaries.

“The wars were great in allowing us not only to develop tactics, techniques, and procedures but gear and technology to match them,” the retired Delta Force operator said, adding that the experience allowed operators to work more closely and more effectively.

“We ‘sharpened our blades’ and learned what works and what doesn’t,” the retired Delta Force operator added. “We would never be able to advance so quickly in peacetime. It’s cynical to say so, but the wars really helped us in that sense.”

Senior leaders at U.S. Special Operations Command, which oversees each service’s special operations units, encapsulated those units’ contributions to the war in a recent letter to the force.

Gen. Richard Clarke, the SOCOM commander, and Chief Master Sgt. Gregory Smith, the SOCOM senior enlisted leader, wrote that they were inspired by the “generation of brave Americans who have answered the call to serve over the last two decades — like the courageous generations before them.”

Special operators serving on September 11 “approached their service with renewed dedication and resolve. Many more have raised their hand to serve,” Clarke and Smith wrote. “Our Special Operations community has distinguished itself through countless acts of heroism and selflessness over almost two decades. That legacy of service and sacrifice continues.”

This article was written by Stavros Atlamazoglou and originally published on the Insider.