WASHINGTON -- China nearly doubled the number of patrols by its fleet of attack submarines last year, surpassing Russia but still far behind the United States, the Federation of American Scientists reported Tuesday.
The report, based on declassified information provided by US naval intelligence, said Chinese attack submarines conducted 12 patrols in 2008, compared to seven in 2007, two in 2006 and none in 2005.
"While the increase in submarine patrols is important, it has to be seen in comparison with the size of the Chinese submarine fleet," said Hans Kristensen, director of the organization's nuclear information project.
"With approximately 54 submarines, the patrol rate means that each submarine on average goes on patrol once every four and a half years," he said.
The patrols may have been carried out by just the most modern and capable types of submarines in the Chinese fleet, the report said, noting that a new class of nuclear-powered Shang-class attack submarines is replacing the aging Han-class.
In an interview, Kristensen said the information, although sketchy, was a window into how Chinese naval operations are changing as it builds up its forces.
"We don't know where they went or for how long. But it certainly seems to be a new mission. They have been very modest in their patrols in the past," he said.
"The fact that from one year to another they have doubled their patrols seems that they have something new to do," he said.
"It could be, as we've heard for the last four years or so, an attempt to expand their naval defense barrier further eastward into the Pacific," he said.
In comparison with other major navies, a dozen patrols a year "are not much," the report said.
"The patrol rate of the US attack submarine fleet, which is focused on long-range patrols and probably operate regularly near the Chinese coast, is much higher with each submarine conducting at least one extended patrol per year," it said.
"But the Chinese patrol rate is higher than that of the Russian navy, which in 2008 conducted only seven attack submarine patrols, the same as in 2007," it said.
China has yet to conduct a single patrol by a ballistic missile submarine, according to the report.
"The old Xia, China's first SSBN, completed a multi-year overhaul in late-2007 but did not sail on patrol in 2008," it said.
"Neither the Xia-class (Type-092) ballistic missile submarine nor the new Jin-class (Type-094) have ever conducted a deterrent patrol," it said.