With President-elect Donald Trump poised to become commander-in-chief, a number of debates have arisen about the legacies that will be left behind by his predecessor and the ways those legacies shape the options available to Trump. Last month in an interview, President Obama outlined five moments that he believed defined his presidency. One of them involved the use of drones to track and kill suspected militants. In a world where a U.S. president has an arsenal of drones at his or her disposal, Obama recalled, America will soon find itself with a president who can carry on perpetual wars all over the world, “and a lot of them covert, without any accountability or democratic debate.”

The notion that drones make it easier for leaders to use military force has raised questions about the proliferation of drones globally, from groups like Human Rights Watch concerned about illicit uses of force to debates in the U.S. government about how to balance proliferation concerns and export policy choices. Discussion of these issues is understandable — the United States is perceived as having been relatively unconstrained with its use of drones around the world. President Obama stated that drones have become a ubiquitous ingredient in our strategy for combatting counterterrorism and are likely to remain so.

What would the world look like if drones played a similarly large role for all modern militaries? This is an important question not just because of the recent U.S. election – which produced a president-elect who will begin formulating a vision for American foreign policy – but also global trends.

Almost a dozen countries now have armed drones. Countries like China and Israel have become major drone exporters. Armed drones are becoming an increasingly mainstream capability.

There are two major schools of thought on the impact of drone proliferation. The first, primarily made up of skeptics about drone strikes outside the U.S. government, suggests that the consequences would be dismal. This view holds that other countries would extrapolate from the U.S. experience and be more inclined to carry out drone strikes of their own, leading to enormous ripple effects – especially in East Asia and the Middle East.

Another perspective, however, is somewhat more sanguine about drone proliferation. Drones, according to this view, do not change the decision-making calculus for states contemplating the use of force. As former Director of Central Intelligence and Secretary of Defense Leon Panetta stated in his memoirs

To call our campaign against Al Qaeda a “drone program” is a little like calling World War I a “machine gun program.” Technology has always been an aspect of war…what is most crucial is not the size of the missile or the ability to deploy it from thousands of miles away” [but how the munitions are used].

In a newly-published article in International Security, we evaluate these two competing perspectives. It turns out, the reality is more context-specific than either side in the drone debate has acknowledged. We examine the consequences of current-generation drone proliferation in six different contexts — counterterrorism, interstate conflict, crisis onset and deterrence, coercive diplomacy, domestic control and repression, and use by non-state actors for the purposes of terrorism – to see how the increasing use of drones might change military outcomes, or even the global balance of power.

Counterterrorism: The operational advantages of drones, including their precision and low risk to their operators, have made drones invaluable to the United States for counterterrorism, and they will likely prove useful to other countries for similar purposes. Drones are effective here in part because regions where counterterrorism strikes are most active, whether Gaza, the tribal regions of Pakistan, or Yemen, lack sophisticated air defenses that are otherwise quite lethal against drones that fly low and slow.

Interstate conflict: Because of their vulnerability to anti-air defenses, current-generation drones are likely to have a minimal impact on interstate relations (or internationalized disputes like the one against the Islamic State). Indeed, as Micah Zenko and Sarah Kreps point out, drones will be unable to take and hold foreign territory because of limits to current drones’ range, speed, and lethality. And because they, like other forms of airpower, cannot take and hold territory on their own.

Crisis onset and deterrence: There are reasons to think that drones could be a stabilizing force in some types of border disputes, especially those among interstate rivals. Drones could give both sides in a crisis real-time information about the situation at lower cost than inhabited intelligence, surveillance, and reconnaissance (ISR) assets – especially for countries without the extensive ISR capabilities of the United States – and with lower risk to personnel, than is possible at present. Similarly, drones could decrease the ability of potential aggressors to conduct surprise attacks. With the aid of surveillance drones, potential targets may be more likely to see attacks coming and prepare accordingly. Drones, then, may be useful for deterrence by denial: If the potential aggressor is dependent on the element of surprise, but knows that drones flying near the border would give the other side adequate notice, it may be less likely to launch an attack.

Coercive diplomacy: At first glance, drones might appear useful for coercive diplomacy because, in theory, they allow the attacker to inflict pain or impose its will at a lower cost. The problem, however, is that current-generation drones cannot operate effectively in hostile airspace, due to their inability to evade enemy air defenses, which makes them poorly suited for denial or punishment. Coercion works only if the coercer has the military capacity to carry out its threat. Drones will usually fail to meet this basic requirement for successful coercive diplomacy.

Domestic control: One of the more consequential applications of drones may be in a domestic conflict setting. Drones, along with other military robotics systems, could provide a new means for autocrats to repress their local populations. Drones can operate from centralized locations where those most loyal to the regime can directly supervise their use. Historically, the unwillingness of large numbers of troops to fire weapons at their fellow citizens has tended to stymie autocratic repression. Drones solve this problem by significantly reducing the number of military personnel who have to be persuaded before engaging in such action. Indeed, in a discussion about the future of military robotics in December 2015, U.S. Deputy Secretary of Defense Robert Work argued that “authoritarian regimes who believe people are weaknesses in the machine, that they are the weak link in the cog, that they cannot be trusted…they will naturally gravitate towards totally automated solutions.” This appears to be happening already. Research on the causes of drone proliferation demonstrates that autocratic leaders are especially likely to seek armed drones.

Non-state actors: Finally, drones are likely to be a useful tool for non-state actors. Small drones could work well for militant groups as a precision weapon where the drone, likely with explosives attached, is the weapon itself. Some groups initially began to use suicide bombing, partially because this tactic provided a high degree of accuracy against either important civilian or hard military targets – the ultimate “smart” weapon. Drones offer a similar level of precision at a lower personnel cost, potentially allowing groups facing manpower shortages to use drones instead of suicide bombs in some situations. The Islamic State used drones in this way in October 2016 when it sent an inexpensive-looking drone equipped with explosives to kill two Kurdish soldiers. The Pentagon has also recognized this possibility, and cited this type of tactic as a major battlefield threat for which they are not immediately prepared. But smaller drones could also be attractive to lone-wolf actors like the Boston Marathon bomber. Drones share many advantages of suicide terrorism in that they can trespass physical ground-based barriers, and then visually identify and target high-density areas.

It is clear from looking at the six types of scenarios above that drone proliferation may have a real impact on armed conflict around the world in the years to come. Their relatively low cost, lack of need for human pilots, high precision, and ability to hover and surveil for long periods of time will make them particularly well-suited to certain conflicts and certain actors. On the flip side, drones’ vulnerability to hostile airspace and limited range, speed, and lethality will make them unlikely to play a significant role in many conflict scenarios.

The proliferation of the drones of today is unlikely to have the transformative effects about which many analysts worry. Current-generation drones are simply not game changing in the way that some prior military innovations have been – for example, the introduction of nuclear weapons. The greatest consequences of current-generation drone proliferation, ironically, may emerge in contexts that receive the least amount of attention in scholarship and policy circles – especially domestic control and repression. This often gets lost, however, in debates about drones due to the tendency to conflate both the drones of today and those of tomorrow under the same umbrella. There is a risk of being so focused on visions of the future of drone technology that analysis of the consequences of current-generation drone proliferation can be exaggerated.

Militaries around the world are investing in a new generation of drones, as well as military robotics designed for ground, naval surface, and underwater operations. And it is undeniable that drone technology is moving quickly, with the development of speed, stealth, and swarms seemingly on the horizon. These advancements could bring drone technology further into the mainstream of interstate war planning and operations. How might this happen?

First, swarming technology could provide ways for coordination between smaller drones to enemy air defenses and provide firepower in their own right. Tests of Perdix mini-drones launched from F-16s and F-18s, supported by the Pentagon’s Strategic Capabilities Office, highlight ongoing research in this arena. These developments are often linked to trends towards miniaturization.

Second, the incorporation of stealth technology could make next-generation drones more survivable against air defenses. This means they would become more useful in denied airspace peppered with anti-access systems.

Third, advancements in the speed of drones could improve their utility, especially in the context of interstate conflict and competition, by making them less vulnerable to enemy fire.

Whether these developments ultimately happen will in part depend on technological change, but also on bureaucratic will, especially in the United States. Rising powers such as China, however, seem intent on pushing the envelope and speeding up their development of next-generation systems. Despite efforts such as the “third offset strategy,” the resolve of the United States to keep pace with these rivals remains unknown.

In sum, technological advancements could hasten a much more transformative consequence for drones in particular and military robotics in general. Our research demonstrates that, beyond the relatively narrow case of targeted strikes, and support for broader ISR missions, the real impact of drones, therefore, is likely to be seen in the mid- to long-term, rather than the near-term.

Michael C. Horowitz is associate professor of political science and associate director of Perry World House at the University of Pennsylvania. You can follow him on twitter @mchorowitz. Sarah E. Kreps is associate professor of political science at Cornell University. You can follow her on twitter @sekreps. Matthew Fuhrmann is associate professor of political science at Texas A&M University. You can follow him on twitter @mcfuhrmann.

Image: U.S. Air Force photo by Airman 1st Class Kristan Campbell