The Trump administration announced last week that it would reverse a 2014 ban on the use of land mines outside the Korean Peninsula. This is a sharp departure from the past 30 years of U.S. land mine policy — and a move the European Union, nongovernmental organizations and Democratic Party candidates have protested.

What does this new policy change mean, and what should you know about land mines?

1. What was the previous U.S. position on land mines?

The United States has not signed or ratified the 1997 Mine Ban Treaty but has refrained from using antipersonnel land mines since 1991 — with the exception of a single mine in Afghanistan in 2002. The United States also has not sold land mines to other countries since 2002.

Governments and citizens alike have widely celebrated global efforts to prohibit and eradicate land mines as a victory in setting norms to limit the destruction of war. The United States has funded land mine clearance operations in several countries, including Angola, Mozambique and Colombia. Between 2013 and 2017, the United States contributed $847.3 million to land mine clearance efforts.

2. Are land mines useful?

The Trump administration explained the new policy as a response to the return of great power competition. Neither Russia nor China has signed the Mine Ban Treaty, and the most recent National Defense Strategy highlighted the return of “long-term strategic competition” with Russia or China as a major concern. Pentagon officials claim land mines are a “vital tool in conventional warfare” and a “force multiplier in key operational contexts.”

Yet both military veterans and humanitarian groups widely discredited these arguments more than two decades ago in the lead-up to the 1997 Mine Ban Treaty. A 1996 Red Cross study found antipersonnel mines generally had little or no effect on the outcome of conflict, and there were zero cases in which the use of land mines played a major role in the outcome of a conflict.

During the Persian Gulf War, U.S. commanders were concerned using land mines could unintentionally kill U.S. troops and were reluctant to use the weapons.

In 2020, both Russia and China have much more advanced weapons — ranging from heavy artillery to counterspace weapons — at their disposal for great power conflict. It’s not clear how land mines would offer a decisive advantage — or what specific circumstances would lead to their use in conflict between great powers.

3. Land mines harm civilians — and alliances

The United States’ use of land mines could also pose problems for any potential conflict that might involve the NATO alliance. All other NATO members have signed and ratified the Mine Ban Treaty, which prohibits them from using, transferring, assisting or encouraging other states (such as the United States) to use land mines.

Beyond the questionable strategic rationale for using land mines, these weapons are also extremely harmful to civilians. Because land mines remain in the ground after conflicts officially end and can be detonated by whomever steps on them inadvertently, they disproportionately kill and wound civilians, not combatants.

More than 120,000 people were killed or injured by land mines between 1997 and 2017. Today, the only country that actively places land mines in the ground is Myanmar. Yet, casualties continue. In 2017, more than 7,000 people — 87 percent of them civilians — were killed or injured by land mines. Only 202 of these casualties were in Myanmar. The rest were from mines previously placed in other countries during past conflicts.

4. What does Trump’s policy reversal change?

It’s not clear how and when the U.S. military might deploy land mines. A news release from the Pentagon notes any proposed U.S. use of land mines outside the Korean Peninsula must have the defense secretary’s approval.

Should the United States use land mines, it would employ “smart” mines that are active for only hours or months before self-destructing, rather than mines that remain dormant until activated. However, even land mines that are active for an entire month would still pose a major risk to civilians during the period before they self-destruct.

Although it is unclear what the probable concrete outcome of the policy change will be, it opens the door for a range of possibilities previously not considered as military options for the United States. The Defense Department cited the possibility of great power war against Russia or China as a motivation for the change in policy, but there do not appear to be any geographical or operational restrictions on the use of land mines under the policy. The United States could therefore use land mines in conflict zones around the world, even in the absence of war with other great powers.

There’s also a risk to U.S. standing in the world, as this policy announcement stands in stark contrast to internationally accepted norms of warfare. Many scholars have investigated the impact of countries’ global reputation for being “good international citizens,” or even how simply being a reliable partner affects their ability to secure the support of other nations and, more broadly, achieve their foreign policy goals.

By bucking the international consensus on land mines, the Trump administration risks undermining support — including among its allies — for U.S. leadership in international relations. As part of a broader trend of U.S. withdrawal or opposition to international agreements, the Trump administration’s reversal on land mine use may contribute to the U.S. reputation as a spoiler in international cooperation.

Naomi Egel (@NaomiEgel) is a PhD candidate in the government department at Cornell University. Her research examines the politics of multilateral agreements to govern weapons.