In light of the beginning of a Russian invasion of Ukraine, NATO secretary-general Jens Stoltenberg has announced plans “to develop options to further strengthen NATO’s deterrence and defense, including to consider establishing new NATO battlegroups in … eastern and southeastern Europe.” France may lead a battle group in Romania, adding to alliance forces in the Baltic states and Poland. While such military presence might serve to deter Russian aggression along the eastern flank of NATO, it would have an additional value: tying down Russian troops along those borders rather than allowing them to be redeployed toward Ukraine. In principle, NATO could challenge Russia with the prospect of second fronts, compelling it to move assets away from Ukraine.

However controversial, exploiting Russian vulnerabilities through second fronts belongs in the U.S. toolkit. Similar opportunities could play a role with regard to China’s intentions to establish control over Taiwan. Yet current strategic thinking has been largely limited to dubious sanctions regimes that have a poor track record of impacting adversaries’ behavior, or to vague plans for defensive responses by Ukraine or Taiwan themselves with no clear U.S. role. What is missing is a program for American and allied engagement that would raise the costs for the enemy through the threat of additional theaters. If Russia or China violate international borders, they should understand that their own borders can come into play. War is still politics by other means.

We would prefer that hard-nosed diplomacy, serious economic sanctions, and a credible military presence in both regions deter Beijing and Moscow from further adventurism. Yet if U.S. policymakers decide that they must use force in response to Russian or Chinese aggression, then we believe that the risks Washington is thereby accepting requires an equally aggressive strategy, particularly given the strengths Russia has developed in land-based warfare and that China has achieved in aerial and naval operations. Likely outnumbered and with extended supply lines, U.S. forces will need ways of dispersing the strength of their adversaries.

Historically, wars have been won by adding a second front, forcing an aggressor nation to fight in multiple theaters and therefore to dissipate its strength. That is a lesson of World War II, when Germany faced the Normandy invasion in addition to the advances of the Red Army in the east, and Imperial Japan fought against the Chinese on the continent and the Americans on the islands of the Pacific. Napoleonic France similarly succumbed to the combination of campaigns by Britain and Russia, as well as to local uprisings in Spain and elsewhere. Multiple theaters in the east and the west during the American Civil War contributed to the overwhelming of the Confederacy.

To change Moscow and Beijing’s risk assessment, Washington has to put the prospect of second fronts on the table. The United States has not waged a major two-front war since 1945 and putting together such a strategy, and executing it, requires hard-headed planning and sophisticated diplomacy with potential partners, not to mention a full commitment of U.S. military capabilities. Below, we offer some thoughts on what two-front campaigns against Russia and China might look like, but we are most interested in sparking off a debate on such a strategy inside U.S. government and military circles, and in those of our allies and potential partners.

Russia has now invaded Ukraine, and plans could be developed to raise the costs for Moscow. Its attack is likely to proceed from the east through the Donbas region and potentially from the north as well, through Belarus. Moscow’s prize target would be an occupation of Kyiv. Ukrainian forces may be able to mount an effective resistance, but they will be under enormous pressure. In this crisis situation, U.S. forces—potentially in concert with Turkey—should challenge the Russian occupation of Crimea in Ukraine’s south. As far as the international community is concerned, Crimea remains part of Ukraine, despite the Russian claims of annexation, so such a campaign would represent a restoration of legitimate rule.

This second front could be opened through the destruction of the so-called Crimean Bridge across the Strait of Kerch that Russia constructed to link its mainland to the occupied Crimean Peninsula. Such an approach could be integrated into a campaign to confront Russian naval presence in the Black Sea, in collaboration with Turkey which, on the basis of the Montreux Convention, controls the Bosporus and Dardanelles Straits. Confronting Russia in Ukraine’s south and in a maritime campaign would force it to reallocate resources from its main attack lines and therefore provide indirect support to Ukrainian forces defending Kyiv. Consideration should also be given to exploiting Russian pressure points further afield, most notably in Japan’s Northern Territories, occupied by Russia as the Kuril Islands, contingent on effective diplomatic preparation with Tokyo. A campaign in Russia’s far east could sap its ability to pursue its ambitions in Ukraine.

In the case of a Chinese invasion of Taiwan, the United States has to go beyond supporting a robust Taiwanese defense, particularly given the adverse balance of power that Taiwan faces in any conflict with China. Opening up new fronts in a Taiwan contingency might see the deployment of U.S. special operations forces along with those of Japan and Australia to neutralize or take over Chinese territory in Spratly and Paracel Islands in the South China Sea, drawing off forces intended to move on Taiwan; alternately, an air campaign to render those islands and their bases unusable could be launched. Land-based fires from Japanese and U.S. Army Pacific forces could be employed to clear the South and East China Seas of People’s Liberation Army Navy and Chinese merchant ships. In either case, we would be threatening Beijing with losing the ability to control those strategic water spaces or utilize them for access to the Western Pacific Ocean.

And, while not a major asset, the Chinese military installation at Djibouti should face similar attacks. We should also threaten those bases throughout the Indian Ocean region, like Gwadar in Pakistan, Kyaukphu in Burma, and Hambantota in Sri Lanka, where China has shown an interest in gaining access. Attacks on enemy shipping, meaning Chinese merchant ships, throughout the Indian Ocean and beyond, would be a natural escalation of control of the sea operations beyond the Taiwan Strait. All this will serve, or could threaten to serve, to make Beijing fear its broader access to the Indo-Pacific commons, should it attack Taiwan.

Action in what Nicholas Spykman called the “marginal seas” of Asia may expand the near zone of conflict, and force Beijing to disperse its military assets outside the immediate range of Taiwan, but such operations may not fully rise to the level of a second front. Though a more complicated strategy, Washington, therefore, should discuss with New Delhi the possibility of joint action along China’s disputed border region with India. Opening a second front here would threaten Beijing with a major escalation in a region it is already concerned about holding. As recently as last fall, Chinese and Indian troops clashed near Tawang in Arunachal Pradesh, which China claims as part of Tibet. Meanwhile, China occupies Aksai Chin which India claims as its own.

There are several other flashpoints of conflict along China’s southwest border in the high Himalayan region. At stake is primarily the border of Tibet. An activation of U.S. support for India’s claims in the region would be consistent with current American interest in building the partnership with India as part of the Indo-Pacific Strategy.

In terms of military actions, drone attacks and special operations against Chinese forward positions would be plausible first steps, once triggered by Chinese action against Taiwan. Should the conflict continue, troop movements could lay the groundwork for border adjustments consistent with Indian claims, including with regard to Kashmir. Here, U.S. Army Pacific forces, staging from Indian territory, would be best employed to either feint into Chinese-held territory or actually engage People’s Liberation Army units, again forcing Beijing to divert needed forces from Taiwan and operate at opposite ends of the country.

Obviously, any joint military action will require delicate negotiations with New Delhi, which will likely be averse to any military conflict with China. However, the opportunity to recapture long-claimed territory and dent Beijing’s presence along India’s borders may at least make quiet discussions and even planning possible, something Beijing is certain to pick up.

Allying with India is a tall order, though not necessarily a chimera. However, more realistic are options to create trouble for China in other areas it considers even more important than the Himalayas. If Beijing invades Taiwan, it should know that it would also face action in Tibet and Xinjiang, and even Inner Mongolia, whether through support for irredentist movements, special operations, or even more direct confrontation. Encouraging anti-People’s Republic of China propaganda campaigns, interfering with communications between Beijing and such outlying provinces, harassing Chinese security units, and outright sabotage by trained local fighters will also serve to force Beijing to maintain territorial cohesiveness by using forces needed for Taiwan.