Over the past four years, international conditions have changed radically and returning to the multilateralism of the Bush-Obama years won’t offer Joe Biden the leverage needed to deal with China and Russia.

The freedom for swift action that authoritarian regimes enjoy permitted China to quickly suppress COVID-19 and register economic growth in 2020, while Europe and North America suffered greatly from the pandemic and a recession.

Confident in the belief that its system is superior, Beijing is pushing out in all directions — repressing Hong Kong, forcibly assimilating ethnic minorities, continuing a naval buildup that threatens U.S. interests and allies in the Pacific, and co-opting the European Union.

Despite China’s human-rights transgressions, the EU recently signed an investment and trade agreement with Beijing. European leaders point to market-opening opportunities, leverage on Beijing’s climate change policies, and commitments to support labor rights.

However, Beijing has broken numerous commitments on trade and investment in the past, is violating its promise to maintain a two-system one-nation policy in Hong Kong, and appears reticent about commitments on climate change.

Globally, China is the largest source of new greenhouse gases, and no possible solution to the planet heating up is possible without curbing its fossil-fuel use. Last September, Beijing pledged to reach peak CO2 emissions by 2030 and net zero emissions by 2060 but China continues to build coal-fired plants. At the December Climate Ambition Summit, Beijing did not table any meaningful initiatives to reverse those plans.

China shows no remorse for failing to warn the world about COVID-19 and has sought to subvert the World Health Organization to avoid culpability. Now it is pressuring Australia and others who support a WHO investigation — and to refrain from taking issue with its treatment of Hong Kong and repression of Muslims in western provinces.

Trade and foreign investment are the cudgels Beijing uses to weaken Western resistance and punish critics. It is investing heavily in Western European companies to access cutting-edge technology and in Eastern and Central Europe infrastructure, and that could undermine loyalty to NATO.

Sadly, the Europeans recognize the security threats it poses but show inadequate interest, save the U.K., in assisting America’s response to China’s military buildup in the Indo-Pacific or to limiting Beijing’s investments in Europe.

Digital technologies are rapidly dividing the world into two spheres.

One led by China, which preaches the benefits of autocratic government and would be happy to provide acolytes with the tools for the surveillance state and repression. The other is led by America and its advanced allies, who offers technology freely to partners to build wealth, prosperity and mutually respected security.

Russia cannot challenge the United States or NATO in conventional weapons, but the potential for a conventional conflict to ignite a nuclear war permits Russia to pursue great mischief without fear of military retaliation, for example, in the Middle East by supporting U.S. rivals and to engaging in cyberwarfare.

Vladimir Putin can test Biden and is no doubt emboldened by the weak response of the Obama-Biden administration to the Chinese hack of the Office of Personnel Management in 2014. The SolarWinds cyberattack has compromised the data security of multiple U.S. agencies and private corporations — and so far without much American response.

Biden’s commitment to multilateralism and shoring up relations with allies is a process, not a policy. It must be accompanied by a clear message about the challenges that China and Russia pose, and that acknowledges a credible response will be costly to Americans and that articulates with firmness and clarity what we expect from our allies to enjoy our protection.

We cannot trade with China on our current scale without peril and must bear the cost of disengagement. The Germans, for example cannot be dependent on trade with China and buy natural gas from Russia without helping finance their military and cyberwarfare infrastructure.

America must shift its military resources to the Pacific and equip the Navy to inflict fast and certain damage the Chinese don’t dare risk. With populations and GDP well exceeding Russia, our NATO allies must pick up the resulting slack in conventional resources in Europe.

This is Rome vs. Carthage — only one side can win. China and Russia see it that way, consequently, so must we.

Biden’s most comprehensive statements on foreign policy have mostly waxed about the importance of multilateralism, but the recent trade and investment treaty China has accomplished with the EU indicates multilateralism and reliance on allies will prove a hollow policy.

Peter Morici is an economist and business professor at the University of Maryland, and a national columnist. He tweets @pmorici1