Russia and China are top threats according to Dunford

In September 2018, Russian armed forces, joined by Chinese and Mongolian troops, gathered in the country's east for Vostok-18, an "unprecedented" military exercise that Russia said was the largest since 1981.

In October and November 2018, all 29 NATO members and Sweden and Finland massed in Norway for Trident Juncture 2018, a regular exercise that this year was the largest version since the Cold War, according to NATO officials.

Joining Trident Juncture was the aircraft carrier USS Harry S. Truman, which sailed into the Arctic Circle west of Norway on Oct. 19, 2018, becoming the first US aircraft carrier to do so since the early 1990s.

These events, plus heightened tensions between Russia and NATO and other close encounters between them, have given many the impression the world has returned to a Cold War.

The U.S. Navy aircraft carrier USS Harry S. Truman.

(U.S. Navy photo by Mass Communication Specialist 2nd Class Thomas Gooley)

According to Marine Corps Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff, that's not the case, but there are now real challenges to US power.

"I wouldn't suggest that it's a Cold War," Dunford said on Nov. 5, 2018 during an event at Duke University. "But if you think about the 1990s," after the collapse of the Soviet Union, he added, "the United States had no competitor, and as we look at Russia and China today, we see Russia and China as peer competitors."

Tensions in Europe have been elevated for some time.

In the early 2000s, not long after Vladimir Putin rose to power in Moscow, the Baltic states of Latvia, Lithuania, and Estonia joined NATO, bringing the alliance into a region that Russia has long considered sensitive.

A decade later, fearing NATO would be invited into strategic areas of the Black Sea region, Russia annexed Crimea in Ukraine and has remained involved in the simmering conflict there in the years since.

Since then, NATO has boosted its presence in Eastern Europe in response, with more US armored rotations and the stationing of multinational battle groups in Poland and the Baltic states.

China, too, has grow in power over the past two decades. It has been increasingly active in its near abroad, making expansive claims over the South China Sea, which its neighbors dispute and an international tribunal rejected.

The US has played a major role in contesting those claims, leading freedom-of-navigation exercises in the region to ensure waterways remain open. That has led to confrontations with Chinese forces on sea and in the air.

But increased tensions don't mean the world has returned to the status quo ante, Dunford said.

Gen. Joseph F. Dunford, Jr., chairman of the Joint Chiefs of Staff.

(Photo by Myles Cullen)

"It doesn't necessarily equate to a Cold War. Competition doesn't have to be conflict," he said during the event. "But ... from a military perspective, we have two states now that can challenge our ability to project power and challenge us in all five domains" — ground, sea, air, space, and cyberspace — "and that's what's different than in the 1990s."

Though he described them as new challenges, he characterized the US response to each of them differently.

During meetings with his Russian counterparts, Dunford said he has tried to "make it clear that what you're seeing in our posture, what you're seeing in the increased forces that we have put in Europe, what you're seeing in the path of capability development that we're on, is in order to deter a conflict, not to fight, and in order to make sure that we can meet our alliance commitments in NATO."

"Russia has made a concerted effort over the last 10 years to increase their capabilities," including at sea, on land, in space and cyberspace, and with nuclear weapons, he added, "So I've tried to explain to them is that what we are doing is responding to that challenge that they pose."

In contrast, in the Pacific region — where the US recently renamed its combatant command as Indo-Pacific Command in what as seen as a compliment to India and a slight to China — the US is trying to ensure everyone plays by the same rules, Dunford said.

"China is irritated by what we do, but again, [we] try to explain to them that, look, there is a rules-based international order, and we talk about a free and open Indo-Pacific based on international law, norms, and standards," he said.

"What we are doing in the Pacific is we're flying, operating, and sailing wherever international law allows, and the purpose of that is to demonstrate that we are standing up for those rules."

In addition to claiming a vast swath of the South China Sea, Beijing has reclaimed land on reefs and islands there and, on some of them, constructed military outposts.

The US and others have rejected those claims and continued to treat the area as international waters, which has led to a number of close encounters.

Dunford encouraged continued diplomacy with China, and he spoke positively about his interactions with Chinese military leadership, saying they had been able to perform "confidence-building measures" and to "increase transparency and reduce the risk of miscalculation."

But he also said a "coherent, collective response" was necessary and that, like other US officials, he had made plain to Beijing the US's objections.

"I learned early in my career that if you see something that is not to standard or not within the law and you ignore it, you've set a new standard, and it's lower," Dunford said Nov. 5, 2018. "When I talked to my Chinese counterpart, I said, look, this is not about a pile of rocks in the Pacific. It's about enforcing international law and a coherent response to your violation of international law."

This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.