Washington (CNN) The Pentagon is making it clear that Russia is to blame after two warships nearly collided in the Pacific on Friday, but while the incident was another tense military encounter involving the two countries, the fact that it took place in China's backyard is raising concerns about growing cooperation between Moscow and Beijing to challenge US's position as the preeminent global power.

Russia and China have each sought to expand their global reach by challenging American military dominance in the air and at sea. But while both countries are have been getting bolder, evidence suggests they have done so independently.

As near-peer rivals to the US, both Russia and China are often aligned in many of their geopolitical views but Friday's incident was unusual because of where it took place.

While the US and Russia have offered different accounts of Friday's incident, all indications suggest it took place in waters off the coast of China.

That is uncommon, according to Carl Schuster, a retired US Navy captain and former director of operations at the US Pacific Command's Joint Intelligence Center.

"The Russians normally harass our ships when they are operating in waters the Russian consider to be within their sphere of Influence (Black Sea, Barents Sea and the waters off Vladivostok)," said Schuster, who spent 12 years at sea on US warships.

Friday's encounter took place two days later Chinese President Xi Jinping and Russian leader Vladimir Putin met at the Kremlin as the two countries are claiming relations are at their "best level in history."

"It seems as if they're working in concert with the Chinese. They're looking at the kinds of things that they can, that they can do in concert with the Chinese to challenge the US. And if it means helping the Chinese out in the Pacific, they will do so," according to retired Air Force Col. and CNN military analyst Cedric Leighton.

"By the same token, they expect the Chinese to help them out in other areas, perhaps in central Asia. So that's where we can see other flashpoints between the US and, on the one hand, and Russia and China on the other," he said.

Russia-China relations at an 'unprecedented level'

In addition to asserting that Russia's relationship with China has reached an "unprecedented level," Putin highlighted their shared views on many geopolitical issues, noting the two countries see eye to eye on several geopolitical challenges, including tensions on the Korean Peninsula, in Venezuela and the conflict in Syria.

Xi called the Russian President "a friend," and reiterated Putin's view, saying that "our cooperation is based on mutual trust."

Since 2013, the two leaders have met almost 30 times, according to Chinese state media. Their last bilateral was at the second Belt and Road Summit held in Beijing in April.

While China and Russia maintain strong ties when it comes to trade, both sides have recently indicated they may be open to working together toward achieving another shared strategic goal -- pushing back against US influence.

Russia has consistently demonstrated a willingness to push the boundaries of international law when it comes to asserting more control over the Baltic Sea and testing US commitments to regional allies like Ukraine, particularly since its annexation of Crimea in 2014.

Last year, Russia captured 24 Ukrainian sailors after aggressively ramming their ship in the Kerch Strait. Those sailors remain in custody despite repeated calls by the US for their release.

There are also recent indications that Moscow is intent on growing its influence globally -- a push that will likely only escalate tensions with the US.

Russia expanding influence in Pacific

As part of that effort, Russia has been expanding its presence in the Pacific region amid growing tensions in the disputed South China Sea -- an issue that is particularly important to China.

Beijing claims almost the entire 1.3 million square mile region as its sovereign territory and aggressively asserts its stake, with Xi saying it will never give up "any inch of territory."

But China is just one of several countries who lay claim to parts of the South China Sea along with the Philippines, Vietnam, Malaysia and Brunei.

US military officials, meanwhile, have vowed to continue enforcing a free and open Indo-Pacific.

Acting Secretary of Defense Patrick Shanahan said last month that the Indo-Pacific region was the US's most important theater from a security perspective. While he did not mention China by name last month during a speech in Singapore, he levied thinly failed criticism toward Beijing for using what he called a "toolkit of coercion."

That toolkit included island-building, deploying advanced weapons systems to disputed areas, engaging in predatory economics and the alleged state-sponsored theft of military and civilian technology -- all activities the US has previously accused China of undertaking.

While the US and China have sparred over the South China Sea for years, Russia has been strengthening ties with countries in the region.

Though Russian warships have become an increasingly common sight in the Indo-Pacific region, they have typically avoided serious confrontations with US forces when operating far from home, making the nature of Friday's incident somewhat out of character for a country that has typically prioritized coastal defense.

Taking the relationship to the next level?

By overtly challenging a US ship in the Philippine Sea, Putin may have been signaling to Xi that he is ready to take their relationship to the next level, according to retired rear admiral and CNN military analyst John Kirby.

"Clearly this sends a strong message to President Xi, from Putin's perspective, that we are on your team," Kirby told CNN's Jim Sciutto.

"We have seen the Russians and Chinese cooperate increasingly ... when it suits their interests," he said, adding that the two countries participated in a major military exercise together just last year.

Top US military officials were quick to condemn the Russian sailors for behavior they characterized as reckless and irresponsible -- a forceful response indicating the incident posed a serious risk to the safety of American sailors.

However it remains to be seen what additional steps the US government will take in response to the incident and whether this type of encounter indicates a broader shift in Russia's relationship with China.

What does seem clear, however, is that Russia is continuing to ramp up its aggressiveness when it comes to confronting US military forces.

"Putin clearly has ordered the Russian Navy to pressure the USN whenever opportunities exist. It may possibly be a show of political support for China while Xi is in Moscow, but more likely to signal that Russia is willing to challenge the US dominance on the world stage and at sea," Schuster said.

"You saw actions in Syria, you saw actions in the eastern Mediterranean, in the Baltic, in the Black Sea, and now in the Pacific. You're seeing them really challenging the United states wherever they can so that they can actually not only assert their dominance in a particular region, but also kind of pave the way to judge and gauge our intentions and more importantly our responses," Leighton added.