With the recent first flight of the Chinese air force's J-20 stealth fighter prototype, there has been a great deal of international attention focused on the People's Liberation Army Air Force's rapid modernization.

But an important corollary has been lost in the hype. Yes, the PLAAF is quickly becoming more modern, but it's also getting a lot smaller. Beijing's emphasis on quality over quantity, at least when it comes to military aircraft, is perfectly normal. Today, nearly all of the world's air forces—including the US Air Force—are taking the same approach, replacing numerous older airplanes with fewer modern ones.

According to a chart published by the Air Force Association, a US advocacy group, in the decade since 2000, the PLAAF has reduced its fleet by half from 2,500 fighters. Beijing accomplished this mostly by retiring 1960s designs such as the J-6 and J-7—rough analogues of the Soviet MiG-19 and MiG-21, respectively. In place of thousands of J-6s and J-7s, the PLAAF has brought into service several hundred J-10s and J-11s, respectively based on the 1980s-vintage Soviet Su-27 and Israeli Lavi.

The US Air Force underwent a similar shrinking initiative in the 1970s and again in the early 1990s—both times replacing thousands of older fighters with hundreds of modern ones. A similar process is currently underway in US air arms, albeit more modestly. Between 2010 and 2020, the American fighter fleet is projected to contract by around 10 percent as new F-22s, F-35s, F/A-18s and armed drones replace jets built in the 1980s.

Based on current trends, by 2020 China will possess probably around 1,000 fighters, most of them modern. According to US Secretary of Defense Robert Gates, just 50 of those fighters will be of the latest, stealthy J-20 design. The US military, by contrast, will possess around 3,000 fighters, around a third of them stealth models.

By historical standards, the United States is set to enjoy an unprecedented measure of superiority in both the quantity and quality of its fighter planes, compared to its nearest competitor. In the 1980s, the Soviet air force's fighter fleet outnumbered the US fighter fleet by several thousand planes, although America's were more modern. A decade from now, the US fighter force will both bigger and more modern than China's.