Unmanned aerial vehicles, or drones, have become one of the weapons most closely associated with the global war on terror.

Hundreds of U.S. drones, also known as remotely piloted aircraft, of various types have spent countless hours tracking terrorists and providing American and coalition troops with early warning.

Drones have also attracted scrutiny for their use in killing enemy fighters with precision strikes — strikes that have often killed innocent civilians as well.

But as the U.S. military prepares for a conflict with countries deemed “peers” or “near-peers” — namely China or Russia — the days of drones dominating the air might be coming to an end.

Steady Hands and Unblinking Eyes

Remotely piloted aircraft are good for three main mission sets: precision strikes, close air support, and intelligence, surveillance, and reconnaissance (ISR).

They’re usually piloted by two operators sitting in a facility thousands of miles away and can stay aloft for tens of hours, becoming an unblinking eye in the sky.

Drones first saw combat in large numbers during the NATO campaign in Bosnia in the 1990s. After the terrorist attacks of 9/11, the U.S. military and intelligence community used the MQ-1 Predator to great effect in Afghanistan and Iraq.

When the Predator retired, the MQ-9 Reaper took up the fight, offering better performance and increased payloads, including a “sword missile” designed to slice through targets rather than explode, reducing collateral damage.

The Pentagon plans to replace the venerable MQ-9 with the MQ-20 Avenger. It’s also working on a stealth-capable drone that will accompany F-22s and F-35s as a kind of “loyal wingman.”

Other drones, including the RQ-4 Global Hawk, RQ-7 Shadow, and RQ-11 Raven, focus on ISR missions and don’t carry munitions. Such drones were a key part of one important but closely guarded mission: helping find Osama bin Laden by tracking his courier.

“Man, drones are awesome. They are so good at what they do that they’ve become an almost must-have to get an [operation] off the ground,” a Green Beret assigned to a National Guard Special Forces group told Insider.

“Everyone loves them. Commanders back in base love them because they can control the fight. The ground force commander loves them because of the situational awareness they bring. We can also use footage from the drones in our after-action reviews to see what went OK and want went wrong. It’s like a football team reviewing last Sunday’s game,” said the Green Beret, who was not authorized to speak to the media.

A RAND study on the air war against ISIS concluded that drones were so important in the fight against the terrorist group that they ended up being overused and overburdened. The study recommended the Air Force purchase more of them to meet the tactical demand.

But is the US military’s heavy reliance on drones prudent?

Keeping Up in the New Age

Remotely piloted aircraft are at their best in an air-superiority environment. Their low speed, limited maneuverability, and non-existent self-defense capabilities — most drones can’t even deploy flares to defend against heat-seeking missiles — make them easy targets for a potent, multi-layer air-defense system that uses radar, aircraft, and anti-air weapons.

For the past 20 years, the U.S. military has been fighting unconventional enemies with almost no anti-air capabilities, something that allowed remotely piloted aircraft to be so effective and popular among commanders.

But China and Russia both have potent anti-air and anti-drone capabilities. In a war with either, the U.S. drone fleet will be much less effective until the U.S. Air Force gains air superiority, if it can at all. Facing a future of limited use, the Air Force has begun training drone pilots for other missions, such as combat search-and-rescue and maritime interdiction.

But great-power competition doesn’t necessarily mean war. Direct conflict between the U.S. and China or Russia might never happen. An indirect war in a third country or through proxies, as in Vietnam, Angola, or Afghanistan, is seen as more likely.

In scenarios where a near-peer combatant wouldn’t be able to employ the full military might, drones can be a game-changer.

Latin America, where the U.S. is trying to counter Russian and Chinese influence, could be the site of such a contest.

The capabilities drones bring are welcomed there “because they were previously out of reach for cash-strapped Central American governments,” said Lino Miani, a former Army Special Forces officer and chief executive officer of AeroEye, a security firm offering aerial surveillance and monitoring to governments and others in the region.

“This is a long way of saying that the United States is poised to provide a much-needed capability that will enhance relationships and erode (or at least deter) China and Russia’s ability to disrupt societies through nefarious means,” Miani told Insider.

In a gray-zone conflict, which takes place below the threshold of open war, private companies could also contribute to advancing U.S. interests, reducing the burden on the U.S. military.

The U.S. remains the partner of choice for most countries in Latin America and has longstanding relationships there, in particular with military and police forces, Miani said.

U.S. Southern Command, the Department of Homeland Security, the State Department, and the U.S. Agency for International Development “all have exercise, training, and operational activities in the region that could all benefit from the employment of drones,” added Miani, who is also the president of the Combat Diver Foundation.

In a near-peer conflict, drones won’t be as effective as they have been against terrorists and insurgents, but they will still have a role on the battlefield — one that may expand as technology advances.

Remotely piloted aircraft still require humans to operate, and drones can only be as effective as their operators and the processes that guide them. As a result, using drones, particularly in combat, will have unintended effects, as shown by the US drone strike that killed 10 civilians in the final hours of the U.S. withdrawal this summer.

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