Speaking today at London's Royal United Services Institute, Esper said the political and economic leverage wielded by the Chinese is already eroding the sovereignty of some nations.
And Russian invasion of Georgia, annexation of Crimea and violation of the Intermediate-Range Nuclear Forces Treaty, as it continued to build up its inventory of strategic arms, shows that Russia is unwilling to be a responsible international actor, he said.
"[We] cannot stand idly by while authoritarian nations attempt to reshape the global security environment to their favor at the expense of others," Esper said. "Doing so would invite continued aggression and diminish our ability to deter future conflicts. As such, America's National Defense Strategy makes it clear that great power competition is once again the primary concern of U.S. national security."
The United States is facing the challenge head-on, he said, but freedom-loving nations must recognize the threats to their security and commit to doing their part to keep the world safe.
Esper said Europe is most concerned about Russia, noting Russia's continued aggression in Ukraine and efforts to serve as a spoiler to peace in Syria.
"Even as far away as Venezuela, we see Russia making allegiances with discredited and failing regimes in an attempt to promote instability," he added. "And right here in the United Kingdom, you know well of the lethal poisonings that occurred in 2006 and 2018.
"To put it simply," he continued, "Russia's foreign policy continues to disregard international norms. This is why the United States, in consultation with our NATO allies, is expanding our presence in Poland, and continuing our close collaboration with the Baltic States. The NATO alliance remains vigilant and continues to adapt, to improve unit readiness, to build a more credible deterrence, and to fight and win if necessary."
During his recent trip to the Indo-Pacific region, Esper said he saw firsthand how China's "One Belt, One Road" initiative is manifesting itself throughout the region. "The more dependent a country becomes on Chinese investment and trade, the more susceptible they are to coercion and retribution when they act outside of Beijing's wishes," he said.
Ultimately, Esper said, this influence trickles down to the security arena, and leads countries to make suboptimal defense decisions for fear of upsetting the Chinese Communist Party and being punished through economic measures or political backlash.
Esper said China has stolen technology to push forward military gains. "Indeed, every Chinese company has the potential to be an accomplice in Beijing's state-sponsored theft of other nations' military and civilian technology."
Chinese companies also pose a risk to the secure and resilient telecommunications infrastructure on which U.S. allies and partners depend for interoperability, intelligence sharing and mobilization, he added.
The secretary said the U.S. National Defense Strategy – based on a three-pronged approach of lethality, partnerships and allies and Defense Department reform — takes into account the realities of today's environment — with a particular focus on the new era of great power competition.
"This is not because we are naive about other threats or seek to rekindle another Cold War," Esper said. "Rather, we are aligned in this focus because of the magnitude of the threats Russia and China pose to U.S. national security and prosperity today, and the potential for those threats to increase in the future."
Deterring potential aggression in the first place, prior to the onset of conflict, is paramount to the strategy, he said.
"This is why we are working with our allies and partners to improve our capabilities, capacity and defense posture throughout our priority regions," the secretary said. "With regard to NATO, our top priorities are burden sharing and unit readiness. While we have made great improvements in recent years, we still have a number of allies not meeting the 2% defense commitment as agreed to under the 2014 Wales Declaration."
Member nations at the alliance's Wales summit agreed to work towd spending at least 2% of their gross domestic product on defense.
"[President Donald J. Trump] has been very clear – and I will continue to push my counterparts — that all NATO members must live up to this obligation," the secretary said. "The strength of our collective response requires that all alliance members be ready to do their part when called. Building this readiness demands greater investments so that NATO forces remain the most highly trained and best equipped in the world."
Esper thanked the United Kingdom for its strong defense investment, noting that it is one of the eight NATO members meeting the target.
"If we are to preserve the peace and order that our nations sacrificed so much for in the past, we must remain vigilant, committed and prepared to respond to aggression where it threatens our interests," Esper said. "I am confident that we will continue to work closely together to maintain the freedoms we worked so hard to achieve."