The staggering rise of China has become one of the most prominent stories of the 21st century.

Key points: A superpower has superior military might, and economic, diplomatic and cultural influence

A superpower has superior military might, and economic, diplomatic and cultural influence The erosion of America's global power may be accelerated by the US' current foreign policy

The erosion of America's global power may be accelerated by the US' current foreign policy China is considered an emerging superpower despite still calling itself a "developing" country

Since the fall of the Soviet Union in 1991, the United States has generally been considered the world's only real superpower, while China is still generally referred to as an emerging superpower.

Some analysts are certain that the Asian giant is well on its way to leaving its developing status behind and will pass the US as a global power in coming decades, while others maintain the US will stay in front for years to come.

Those who argue against the US's unrivalled status suggest the very concept of a superpower is losing its relevance in an increasingly "multi-power" world while maintaining that the Western giant no longer meets all the required criteria.

For example, while the US continues to wield the most superior military capabilities on Earth, it is losing its dominant role in world affairs and calling the shots on the global economic stage.

But what does it mean to be a "superpower" in 2019? How will we know if or when China has rivalled or passed the US? And are recent phenomena like the rise of US President Donald Trump to blame or are we witnessing the transformative stages of a future inevitability?

What does it mean to be a superpower?

The US is currently the only global military power, according to the World Economic Forum. ( Reuters: Juan Anaya/US Marine Corps )

Perhaps surprisingly, there is no official definition of what constitutes a superpower — but according to a range of definitions, a superpower is typically characterised by a state's ability to exert influence and project itself as a dominating power anywhere in the world.

There are several measurements of power which include military and economic strength, as well as diplomatic and cultural influence — a superpower should be a leader in all of these areas.

A country's power is measured in different ways. ( ABC News: GFX/Jarrod Fankhauser )

International relations and US policy expert Gordon Adams told the ABC that if power were solely measured in military terms, there is no question the US is the only military superpower.

According to the World Economic Forum, the US is currently the only global military power with the ability to plan, deploy, sustain and fight on a scale and at a distance from its homeland across the land, sea, air and space in a way that's just not possible for any other country.



However, when other dimensions of powers are considered, Dr Adams said the US's leading status becomes a little murkier.

"From 1945 until probably the end of the Cold War, [the US was] single-handedly the nation that could set the agenda, that called the meetings — whose participation was essential," he said.

"It created organisations ranging from the United Nations to NATO, that were at the centre of diplomatic activity in the world."

While the United States isn't the only superpower that has ever existed — the Soviet Union was considered a superpower until its dissolution in 1991 — Dr Adams said it has been the most globally influential and modern one.

And while China is still a distant second in terms of military spending — roughly $US250 billion versus America's $US620 billion — its meteoric rise as a developing country to one of the biggest contributors to world economics, its growing diplomatic pushes, as well as its advances with technology and artificial intelligence, have all called into question the lack of definition in calling the US the world's only superpower.

Why might the US be losing its superpower status?

Dr Adams says the United States no longer calls the tune in the Middle East. ( Reuters: Ahmad Nadeem )

Maria Rost Rublee, associate professor of international relations at Monash University, said the United States is still the closest to what is understood to constitute a global superpower, but added that it increasingly isn't meeting all the criteria for one.

"They need to be the dominant power not [just] militarily, but politically and economically, and the US is clearly not economically," she said.

"In fact, the current conflict with China demonstrates this."

"For example, China has made some noise about no longer buying US bonds — if China stopped buying US bonds and sold all the bonds it held, that would make it very difficult for the US economically."

Dr Adams said there's no question the Chinese economy is becoming "a very serious rival" adding that globalisation has dispersed economic power widely around the globe.

He also pointed to China's trillion-dollar Belt and Road Initiative (BRI) while adding that the US no longer sets the agenda or calls the tune in the Middle East — instead, the most influential countries in the region are now Turkey, Iran and Saudi Arabia.

"What we're moving into is what you would call a multi-polar or a multi-power world," Dr Adams said.

"We're seeing a rebalancing of power among the nations in the world, and, of course, the persistent rise of powerful actors who are not nations whether they're terrorist organisations or multi-national corporations that are increasingly important actors on the world stage.

"So we're seeing the old architecture of power completely redistribute over time and it's systematically eroding any capacity of the US to actually lead."

Why it might take decades to see the US's status decline

Dr Beckley says the United States has four times as much wealth as China. ( Reuters: Thomas White, File )

However, political scientist Michael Beckley and author of the book Unrivalled: Why America will Remain the World's Sole Superpower, maintains that the US is the only country with the military, diplomatic and economic assets to be a decisive player in any region of the world.

Dr Beckley noted that the United States accounts for 25 per cent of global wealth, 35 per cent of world innovation, and 40 per cent of global military spending.

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He told the ABC that America still had a "huge lead" over other countries — for example, it still has four times as much wealth as China and five to six times the military capabilities.

"That gap would take decades to close even if things go very badly for the United States," he said.

But Dr Beckley believed things are unlikely to go badly because the US has "the best fundamentals for future growth".

"The United States has the richest and most secure land on the planet, the most productive population, and a political system that — though far from perfect — is better at spurring entrepreneurship and innovation than the corrupt regimes in China or Russia," he said.

"Nothing is guaranteed in world politics, but what we can say for sure is that the United States has a huge lead and massive advantages over its competitors."

How Donald Trump might be eroding the US-China gap

The erosion of America's global power may be accelerated by the current US foreign policy. ( AP: Carolyn Kaster )

Dr Adams agreed that America remained a powerful country, but said the erosion of its global power, which has already been happening for some time, has accelerated under Mr Trump's leadership.

He said the rules-based international order that has been in place since the end of World War II has been upended by Mr Trump who has pulled out of treaties, denigrated allies and started trade wars since his election.

"His behaviour is speeding up the pace at which the American power erodes, the role of the US erodes, [as] other nations begin to rise and play an important role on the global stage," Dr Adams said.

"Now you're really seeing a reshuffling of the deck internationally."

The Lowy Institute's recently released Asia Power Index also showed a shrinking power differential between the US and China, in part due to the Trump administration's policies.

The report said the current US foreign policy may be accelerating this trend, and that the administration's attempt to rebalance trade flows one country at a time "has done little to improve the glaring weakness of US influence".

In fact, the report ranked Washington behind Beijing and Tokyo for diplomatic influence in Asia partially due to contradictions between the United States' "revisionist economic agenda and its traditional role of providing consensus-based leadership".

However, Mr Trump told Fox News' Steve Hilton last month that he was "very happy" with the trade war with China and that Beijing wouldn't replace the US as the world's superpower while he is in office.

Is China on its way to overcome the US as a superpower?

Sorry, this video has expired China's 40 years of economic reform and opening up.

Economist Sara Hsu said that while China could be described as an emerging superpower, it has also recently slowed the pace of its many reforms that have been fuelling its growth.

Dr Hsu said the changes being made were also insufficient to transform China into a real market-based economy to compete with the US and other developed economies, while adding that China's success with its Belt and Road Initiative is also yet to unfold.

"If China is successful in spreading its soft power to other countries by helping them build viable infrastructure, this can boost China's status, but it will take time and hard evidence that China has what it takes to foster development partnerships in the global south," she said.

But to be recognised as a true superpower, Dr Hsu said China needed to first reach developed-country status to earn the respect of other developed nations.

"For example, superpowers don't need to undergo a 'toilet revolution' to improve access to sanitation," she said.

Meanwhile, despite being the world's second-largest economy, China continues to self-allocate itself as a "developing" country and enjoys the same "special and differential treatment" afforded to nations like Papua New Guinea and Zimbabwe.

However, analysts don't believe China's developing country status would restrict it from being an economic superpower.

"There are estimates that the Chinese economy is going to surpass the US economy on a number of measures by around 2030," Dr Rublee said.

"Even with the [economic] slowdown, it still has higher rates of growth than most countries and superpower status is only relative."