How To Stop an Invasion | Opinion

Invasions are unfortunately relevant again. The military aid package signed on April 24 is a much-needed lifeline for Ukraine's flagging fight against Russia. But the United States needs to double down on a little known but very effective irregular approach: resistance warfare. America should do this with Ukraine, enabling them to ramp up resistance activities, as well as broaden these efforts to other friendly frontline partners and allies.

Despite losing ground as of late in the overall war, Ukraine is teaching the world a masterclass in resistance warfare, an asymmetric approach to self-defense. The Defense Department defines resistance as "a nation's organized, whole-of-society effort," both violent and non-violent, to "reestablish independence and autonomy within its sovereign territory that has been wholly or partially occupied by a foreign power."

Using this approach, the badly underestimated Ukrainian forces and brave citizens repelled Russia's attempts to take Kyiv in the early days of Russia's full-scale invasion. Since then, the resistance has continued to defend, retake, and resist in occupied areas—currently about 18 percent of Ukraine.

Ukraine's harrowing but largely successful experience with resistance warfare offers three main lessons. First, domestic leadership and will to fight is key. Outside partners can assist, but not lead, resistance efforts. Second, a sound legal framework and advance planning are critical to success.

Third, outside support should be long-term and focus on cultivating deep relationships with local officials and helping partners build the institutional framework needed to responsibly oversee and sustain resistance warfare operations. These lessons align with past findings on what has shaped success or failure in resistance warfare over the past 70 years, dating all the way back to World War II.

In July 2021, the Ukrainian Parliament passed a national resistance law. It provided the legal framework of the dispersed resistance movements—led by Ukrainian special forces, reformed the country's territorial defense forces, and helped prepare regular citizens.

The National Resistance Center, created in February 2022, teaches nonviolent resistance and has established underground communication channels. The center leads hands-on workshops, online courses, and produces training manuals. More than 100,000 people have downloaded the manuals.

There is no typical Ukrainian partisan, according to Ostap, a representative of the center who spoke to Newsweek, giving only his first name for security reasons. "There are different people—some young, some older, even grandparents who share information. These individuals are eager to aid the Armed Forces," he said.

A strike in Kherson Oblast in August 2023 occurred after Ukrainian civilians stole a flash drive with information about the location of Russian training. "We knew where and when there would be a crowd there and our forces struck. It was possible because people transmitted the information," said Ostap.

Ukrainians clearly have the will to fight and have admirably led their resistance, both military and civilian. While Ukrainian bravery and skill should take much of the credit, a little-known U.S. effort to help build Ukrainian resilience and resistance capabilities over the 2014-2022 period was also key. U.S. support—led by U.S. special operations forces—prioritized long-term relationships, the building and strengthening of defense institutions geared to support resistance warfare operations, and assisted Ukrainian-led preparations in other relevant areas, including information operations.

This small footprint support appears to have paid off. Richard Clarke, commander of U.S. Special Operations Command, said in April 2022 that U.S. efforts "directly contributed to the success on the battlefield."

Russia's invasion of Ukraine is the starkest illustration of this troubling return to territorial aggression, but more may be on the way. On April 17, House Speaker Mike Johnson said that other Central and Eastern European countries could be Russia's next target, while the top U.S. general in the Asia-Pacific recently testified that China could be ready to invade Taiwan as early as 2027. Resistance warfare capabilities will be vital to meet these growing threats, and are especially needed in non-allied partners in dangerous neighborhoods, such as Moldova, Georgia, and Taiwan.

So what should be done? The United States needs to help prepare the democratic world to fight back. The U.S. and like-minded partners should urgently heed lessons from Ukraine and dramatically increase asymmetric support. While each partner has its own unique history and other limiting—or enabling—factors, Taiwan and Moldova would be good places to start.

America should encourage these partners to own the process of setting up legal and policy frameworks, support the organization of volunteer structures and auxiliary forces, and help partners acquire the right defense systems and tactics. Doing so would help them be protected from invasion with relatively modest but targeted investments and strengthen deterrence in these hotly-contested neighborhoods.

This support tool also helps avoid escalation, as resistance warfare preparations are clearly defensive in nature, not offensive. Russia and China would be forced to think long and hard before launching their next invasion. If they decide to invade anyway, this support will help impose significant costs.

Invasions are back. Supporters of the rules-based international order must act like it and step up efforts to counter them.

Alexander Noyes is a fellow in the Strobe Talbott Center for Security, Strategy, and Technology at the Brookings Institution and former senior advisor in the Office of the Secretary of Defense for Policy.

Elina Beketova is a Democracy Fellow at the Center for European Policy Analysis (CEPA), focusing on the occupied territories of Ukraine. She worked as a journalist in Crimea, editor, and TV anchor for news stations in Kharkiv and Kyiv.

The views expressed in this article are the writers' own.