In 1995 and 1996, Taiwanese politicians signaled greater support for declaring their island country officially independent of China. Beijing’s response was swift, forceful … and ultimately an embarrassment to China. The Chinese fired several missiles toward small, Taiwanese-held islands.

That’s when the United States intervened in a big way, sending two entire aircraft carrier battle groups into the waters around Taiwan — and even sailing one carrier through the Taiwan Strait.

The Chinese military was powerless against this show of force. Beijing couldn’t even reliably track the American warships, and had no forces of its own capable of threatening the powerful U.S. vessels.

The Chinese backed down.

Nineteen years later, the situation has changed. According to the California think tank RAND, if the same crises occurred today, Chinese submarines could target a U.S. flattop several times during a weeklong campaign. “China has rapidly improved its ability to reliably locate and to attack U.S. carrier strike groups at distances of up to 2,000 kilometers from its coast,” RAND warned.

Beijing’s ability to target carriers from below the sea depends on two related capabilities. First, China needs modern and reliable submarines. Second, these subs need some way of finding the flattops.

As far as its sub fleet goes, China has made great progress in the two decades since the 1996 crisis. “In 1996, China had taken delivery of only two submarines that could be described, by any reasonable definition, as modern,” RAND explained. “The remainder of its fleet consisted of legacy boats based on 1950s technology, lacking teardrop shaped hulls and armed only with torpedoes.”

By 2017, China will possess a smaller but more capable undersea fleet with 49 modern subs. “China’s recent submarine classes are armed with both sophisticated cruise missiles and torpedoes, greatly increasing the range from which they can attack,” according to the think tank. “Although most Chinese boats are diesel-powered and none is not up to U.S. standards, they could nevertheless threaten U.S. surface ships.”

Just how much Beijing’s subs could attack a single American carrier during a seven-day campaign depends on what RAND called “cueing.” In other words, the ability of Chinese satellites, drones, spy planes, land-based radars and other so-called “intelligence, surveillance and reconnaissance” systems, or ISR, to detect the carrier and pass along the flattop’s location to the subs.

“Improvements to Chinese ISR have improved the chances that Chinese submarines will receive such information,” RAND reported.

In 1996, Chinese subs had basically zero chances to take a shot at a U.S. carrier, with or without cueing. By 2010 that was no longer the case. Without cueing, Beijing’s subs were still pretty much blind, but with help from ISR the undersea vessels would have gotten two or three chances to attack a carrier with missiles or torpedoes.

RAND projected that, in 2017, Chinese subs with no cueing probably still won’t be able to attack a carrier. But with cueing in the same timeframe, the undersea warships could get three, four or even five chances to attack.

Of course, a chance to attack doesn’t guarantee a successful attack. And the U.S. Navy isn’t exactly standing still as Chinese forces improve, RAND pointed out. “The United States will look to counter this growing threat by developing ways to degrade Chinese intelligence, surveillance and reconnaissance capabilities and by improving its own anti-missile, anti-submarine and defensive counterair capabilities.”

This piece first appeared in WarIsBoring here.