LONDON (BLOOMBERG) - For a quarter century, the United States and its allies owned the skies, fighting wars secure in the knowledge that no opponent could compete in the air. As tensions with Russia and China surge, that is no longer the case.
Rapid technological progress in China's aerospace industry, particularly air-to-air missile systems fired from an aircraft, is changing the game for Western air forces and the global arms trade. It is also altering the picture for China's neighbours such as India.
Russia took the lead in modernising its air force, and has been more willing to use it. In the longer term, however, China's roughly US$13 trillion (S$17 trillion) economy and growing wealth mean it is likely to pose the greater strategic challenge for the US and its allies.
In 2017, Chinese defence spending rose by 5.6 per cent in constant US dollar terms, while Russia's fell by 20 per cent, according to the Stockholm International Peace Research Institute. China spent US$228 billion in 2017 and Russia US$66.3 billion, the institute said.
"We had an environment where we could do whatever we wanted in the air, and what the Chinese have done is to say you no longer can," said senior fellow for military aerospace Douglas Barrie at the International Institute for Strategic Studies. As a result, US commanders now have to take into account potential loss rates for pilots and aircraft that they have not had to face since the 1980s.
The US air force remains the strongest by far. Yet the Chinese advances come at a sensitive time, as the US appetite to continue its role as global policeman fades.
Meanwhile, President Xi Jinping has set ambitious goals to dominate advanced industries such as robotics and artificial intelligence and to assert Chinese interests in the disputed South China Sea and beyond.
The catch-up by Russia and China has been a long time coming, triggered in each case by shock at the ease with which the US air force demolished opponents in the 1990s, according to Dr Vasily Kashin, a specialist in military aviation at Moscow's Higher School of Economics at the National Research University.
For China, that moment came during the first Gulf War, when an American air campaign swiftly crushed the Iraqi military, at the time better equipped than China's. For Russia, he said, the wake-up came in 1999, when a US-led bombing campaign forced Serbia to withdraw troops and tanks from its own province, Kosovo.
Taiwan - which China considers a province - has also been a factor for Beijing. The US called in two aircraft carrier battle groups to support the island during a dust-up with China in 1996 and has provided US$18 billion in arms since 2008.
Some of China's biggest strides are coming in air-to-air missiles, the weapons that for one or two million dollars can destroy a US$150 million aircraft. That is a cost-efficient way of trying to level the playing field with the US.
China's defence budget is well over three times as big as Russia's or India's, but still much lower than the US$610 billion the US spends, according to the Stockholm International Peace Research Institute.
In March, the US Air Force awarded a half-billion-dollar contract to supply close allies with Raytheon's latest long range air-to-air missile, capable of hitting enemy planes from 100 miles (160km) away. The Meteor, a new European equivalent, may be even more deadly. But China's latest offering, the PL-15, has a greater range than either.
The PL-15 also supports an active electronically-scanned array radar that makes evasion difficult for the most agile of fighter jets. Russia has yet to succeed in equipping its own missiles with the technology. When the PL-15 was first tested in public, then-US Air Force Air Combat Command chief Herbert "Hawk" Carlisle was concerned enough to call on Congress to fund a response.
Another Chinese air-to-air weapon in development, provisionally known as PL-XX, would strike slow-moving airborne warning and control systems, the flying neural centres of US air warfare, from as far away as 300 miles. At closer quarters, China's new PL-10 missile is comparable to the best "fire-and-forget" equivalents, meaning any dogfight would likely end with a so-called mutual kill, a significant deterrent.
"In the United States we've been on holiday for 25 years and maybe a little bit more," Dr Michael Griffin, under secretary of defence for research and engineering, said in a recent address to the Hudson Institute, a Washington think tank. "We failed to continue to fund the practices that had gotten us where we were, which was at the very top of the technological heap."
Dr Griffin said he was especially worried by Chinese and Russian progress in developing carrier-fleet killing hypersonic missiles that the US, as yet, lacks the space-based capacity to detect in time to shoot down. The planes to deliver China's new armoury of missiles have also improved dramatically, with new fleets developed from Russian air frames.
This year (2018), the air force is set to receive the last of 24 state of the art SU-35S fighters from Russia, while China has begun deploying the Chengdu J-20, a homegrown stealth fighter.
Combat modelling by think tank Rand Corp found that China last year, for the first time, had achieved parity with the US in air superiority for any conflict close to its mainland, including over Taiwan.
To be sure, China still has a long way to achieve conventional - let alone nuclear - parity with the US at a global level. Its jet engine technology remains weak and reliant on Russia, while its suite of new weapons are largely untested in combat. So are its pilots, still considered inferior to their Western counterparts in training and tactical skills.
Yet Chinese pilots, planes and weapons do not have to be better than their US counterparts to radically change battlefield calculations. The J-20, for example, has poor engines and is thought by aviation experts to be more easily detected from the rear and sides than a US F-22 "Raptor". But it would be hard to spot on approach and has a large weapons bay capable of hiding anti-ship missiles. That makes it a considerable threat.
China's new aircraft, combined with the latest air-to-air, cruise, anti-ship and Russian S-400 air-defence systems - considered the world's best - "have made the ability of the US to operate in contested areas very high risk," said Mr Tim Heath, a senior international defence researcher at Rand.
This shift is not just important for the US. India has watched with trepidation as Russia supplies Beijing - and Beijing supplies Pakistan - with more sophisticated weaponry.
China and Pakistan have co-produced the JF-17 fighter since 2007, with Russia providing high quality engines. In March, Chinese media reported the JF-17 will be upgraded with active array radar, allowing it to detect and fire on targets from a greater distance.
According to Dr Rajeswari Pillai Rajagopalan, Russia's potential approval for China to resell its jet engines to Pakistan was the most frequent topic of discussion at weekly meetings of the National Security Council when she was assistant secretary to the NSC Secretariat from 2003-2007. If Pakistan's jets were equipped with the new radar and China's PL-10 missiles, now available for export, India's ageing Russian MiGs would struggle to compete, she said.
The arms sales are symptomatic of a much more worrying regional realignment of Russia- traditionally India's biggest arms supplier - with China, said Dr Rajagopalan, now head of the Nuclear and Space Policy Initiative at the Observer Research Foundation, a New Delhi think tank. "The Russians are in a weak position now, and they feel it is better to be in the Chinese camp," she said.
India last month (April) put out an international call for bids for a US$15 billion contract to provide 110 new combat aircraft. Pakistan has just over 100 JF-17s and is producing 25 new ones a year.
Beijing's technological progress is also having knock-on effects beyond South Asia. China has moved from its traditional position as a provider of cheap small arms to poor nations, to become the world's number three arms trader in volume terms. That includes the sale of armed drones to Saudi Arabia, Iraq and other nations to which the US declined to sell its Reaper drone technology.
Some missiles China developed with Russian help are now considered as good if not better than the originals, and are on the international market.
Russia, at least, is not overly concerned by competition from the expanding military capabilities next door, according to Dr Kashin. "They are certainly a growing power," he said of China. "But they are not omnipotent, and they are Russia's partner."