China and Japan are redefining the nature and purpose of the Coast Guard. Americans still think in terms of air-sea rescue or chasing drug smugglers when they think about their Coast Guard. China and Japan think about their Coast Guards in terms of realpolitik.

The two nominally civilian services are on the front lines of territorial disputes in the South and East China Seas. Both countries are adding to their coast guard fleets at a breakneck pace. One could almost call it a Coast Guard arms race, except that the vessels are lightly armed if armed at all.

Japan is reinforcing its Coast Guard contingent in the waters around the disputed Senkaku Islands in the East China Sea with 10 new 1,500-ton patrol craft and two new helicopter- equipped vessels. This is in addition to six other cutters already in the region. Tokyo will no longer have to borrow vessels from other Coast Guard districts allowing them to concentrate on routine Coast Guard duties such as rescuing ships in distress.

Tokyo is also overhauling its main operational base on the island of Ishikagi, the closest Japanese island to the Senkakus, with enlarged port facilities to handle the new vessels. It is close to another small island where Japan recently opened an army garrison to protect a new radar base (a well as asserting sovereignty in case China expands its designs on other islands in the Ryukyu chain.)

Both Japan and China assert their claims to the uninhabited Senkaku islands with coast guard cutters rather than ships of their regular navies. On an average of once every two weeks, two or three Chinese Coast Guard vessels enter Japanese territorial waters. They stay for a couple hours then leave. Meanwhile, Japanese Coast Guard vessels regularly patrol the disputed waters ordering anyone inside the territorial zone to leave.

China is also expanding its fleet and building ports of call to maintain them. The growing fleet allows Beijing to assert its claim and support its interests over the entire South China Sea. At present, Coast Guard ships are stationed near the Scarborough Shoal claimed by the Philippines; another routinely patrols the Laconia Reefs off the coast of Malaysia.

While it once depended on former naval frigates, China is now commissioning purpose-built cutters. It is currently commissioning two of the world’s largest Coast Guard cutters, ships that could alter the balance of power in the South and East China Seas (one ship is to be stationed in each sea).

Known only by their hull numbers, in this case Haijing 2901 and Haijing 3901 (the first digit denotes which sea it is to patrol). They displace 10,000 tons, possibly more when fully outfitted. That makes them larger than the U.S. Navy’s Ticonderoga- class cruisers and Japan’s 6,500-ton Shikishima- class Coast Guard cutters previously the largest in the world.

The U.S.S. Forth Worth, a Littoral Combat ship based in Singapore, which has undertaken Freedom of Navigation patrols in the Spratly islands, displaces a mere 1,200 tons. A warship like the Fort Worth could, of course, defend itself from a Chinese maritime enforcement vessel on a collision course, but it would mean firing the first shot.

This may be a coast guard “arms race” except that the competing vessels are not heavily armed. The new Japanese cutters are armed with 20 mm cannons and water cannons. The new Chinese super cutters are not necessarily heavily armed either. Pictures that have been published so far show that they lack gun turrets. It is not armaments that make these two Coast Guard Dreadnaughts so formidable; it is their sheer size.

Coast Guard vessels are not true warships. Usually, they are armed with machine guns or at most medium caliber deck guns, if they are armed at all. The Larger Japanese Coast Guard vessels are armed with 40 and 22 mm guns. But even without a lot of firepower, these new coast guard vessels, especially the new super cutters, can throw their weight around.

The military version of the People’s Daily, the press organ of the Chinese Communist Party, boasted that these powerful new ships could ram and possibly sink a 9,000-ton vessel without damaging itself. That makes them a potential threat to regular naval vessels of the U.S. and Japanese navies.

Ramming has been a tactic in territorial disputes in both the East and South China Seas, harkening back to the days of the Romans and Carthaginians. A large Chinese fishing vessel rammed a Japanese Coast Guard cutter near the Senkakus in 2011. Earlier this year another Chinese Coast Guard vessel rammed one of its own fishing trawlers that had been taken into custody by Indonesian authorities for allegedly illegally fishing in Jakarta’s 200-nautical miles exclusive economic zone.

Retired USN Captain James Fanell, formerly chief of intelligence for the U.S. Pacific Fleet, calls the Chinese Coast Guard, “A fulltime marine harassment organization. Unlike the U.S, Coast Guard, the Chinese service has no other mission but to harass other nations into submitting to China’s extravagant claims,” he says.

Fanell notes that China is building new Coast Guard vessels, like the two super cutters, at “an astonishing rate.”

The regular navies of Japan and China generally stay in the background, but Tokyo is also suspicious about the recent activities of the regular Chinese Navy in waters near the disputed islands. A contingent of Chinese frigates now hovers about 70 km away from the Senkaku, close enough to come to the aid of any of its coast guard vessels that gets in trouble.

For its part, the Japanese government recently made public what the cabinet had decided earlier in the year, that Japanese naval vessels might intervene should the Coast Guard be unable to do its normal “policing” duties. “If it becomes difficult for the police and the Japan Coast Guard, then the Maritime Self Defense Force (navy) could respond,” said defense minister Gen Nakatani. That could happen if Chinese navy ships actually entered Senkaku waters.

The use of “white hulls,” mostly unarmed or lightly armed Coast Guard cutters, rather than “gray hulls,” has been a stabilizing element in the numerous territorial encounters of the past few years. But the recent remarks suggest that Tokyo expects to see more gray hulls than white hulls in the coming year.