Once Again, China and Its Sea Lines of Communication

It's about time to revisit the importance of "sea lines of communication" or, as I referred to them back in 2005, "sea lanes":

I keep posting about sea lanes. What are these things? Sea lanes are trade routes - almost like highways in the sea, where due to geography, ocean going vessels follow certain paths to avoid islands, shallows and other impediments to their travel. They are also generally the most efficient routes to get from Point A to Point B - as close to straight line travel as a ship can accomplish given the number of obstacles in its path.

Chokepoints: Maritime Economic Concerns in Southeast Asia Institute for National Strategic Studies, Washington,D.C. (National Defense University, 1996)
(color and bursts added)

Of particular interest in recent days are the sea lanes China is working to find ways to protect. As you can see from the following (which just reference crude oil shipments) these lanes are heavily travelled. In the first chart, I have marked U.S. allies in blue (yes, Singapore is oversized) and areas that China is making claims or working to establish relations as red bursts. Note that the red bursts sit athwart the sea lanes.

China has a problem, though, in that all the approaches to its ports must first pass through various chokepoints - some of which are very narrow like the Strait of Malacca and some of which are wider.

As set out SLOC Security in the Asia Pacific by Professor Ji Guoxing (2000):

The South China Sea provides shipping routes connecting Northeast Asia with Southeast Asia and the Middle East. The Spratly Islands are located in the southeast quadrant of the sea, an area known to seafarers as 'dangerous ground' due to the shallowness of the waters surrounding the islands and numerous submerged reefs around. Thus most merchant ships steer clear of the Spratlys, and major routes pass well west of the Spratlys. ''Through the South China Sea pass more than 41,000 ships a year, more than double the number that pass through the Suez Canal and nearly treble the total for the Panama Canal.''[2]

There are several straits of strategic importance in the region, such as the Straits of Malacca, Sunda, Lombok and Makassar in Southeast Asia, and the Straits of Tsushima, Tsugaru, Osumi, and Soya (La Perouse) in Northeast Asia. Major shipping routes in the Asia Pacific are through these key straits. Due to their potential for closure, these straits are known as chokepoints.

The Strait of Malacca, 600 miles long, is relatively shallow (only 21.8 meters) at some points. The maximum draught recommended by the International Maritime Organization (IMO) for passing ships is 19.8 meters. The navigable channel at its narrowest point in the Singapore Strait at its eastern end is only 1.5 miles wide. This creates a natural bottleneck, with the potential for collision, grounding, or oil spill.

The Strait of Malacca, being the main corridor between the Indian Ocean and the South China Sea, has as many as 220 ship movements in both directions per day at present, and would have 275 ship movements by the year 2000. ''About 26 tankers, including three fully loaded supertankers heading for Asian ports, pass through the strait daily.''[3] Tankers using the waterway by 2010 will be two to three times more numerous than today. ''If the strait were closed, nearly half of the world's fleet would be required to sail further, generating a substantial increase in the requirement for vessel capacity.''[4]

The Lombok Strait is wider and deeper than the Strait of Malacca, and passing through it is only 150 miles longer. As its depths are greater than 150 meters, it is not draught-limited, and its minimum passage width is 11.5 miles. It is thus used by largest ships over 100,000 DWT (dead weight tonnage). Most ships transiting the Lombok Strait also pass through the Makassar Strait, which has an available width of 11 miles and a length of 600 miles. Its depth is 930-3392 meters, mostly suitable for submarines and large ships.

The Sunda Strait is 50 miles long and is another alternative to the Malacca Strait. Its northeastern entrance is 15 miles wide. But because its northern part is relatively shallow with dangerous currents, it is not heavily used, and deep-draught ships of over 100,000 DWT do not transit the Strait.

The Strait of Tsushima, being part of the Korea Strait, is the major link between the East China Sea and the Sea of Japan. It is 137.9 miles long. Its narrowest point is 25 miles wide, and its deepest point is 129 meters. It is heavily used by vessels traveling to and from the east coast of South Korea, western Japan, and Vladivostok of Russia.

The Strait of Tsugaru, located between Japan's Hokkaido and Honshu Islands, connects the Sea of Japan with the North Pacific Ocean. It is 71.5 miles long. Its narrowest point is 10.1 miles wide, and the deepest point of the navigable channel is 521 meters.

The Osumi Strait is a major connection from the Yellow Sea and the East China Sea to the Pacific.

The Strait of Soya (La Perouse) connects the Sea of Japan with the Sea of Okhotsk. Its narrowest point is 20 miles wide, and its depth is 30-60 meters.

For straits used for international navigation, some regional countries have modified the width of their territorial sea. In spite of their declaration of 12 nautical miles (nm) territorial seas, both Japan and South Korea have modified their territorial seas to 3 nm in the Korea Strait, thus providing a high seas ''corridor'', through which ships may transit without entering the territorial seas of Japan and South Korea. Japan has also declared territorial seas of 3 nm wide in the Tsugaru, Osumi, and Soya (La Perouse) straits.
***
The Asian Pacific countries rely heavily on intra-regional and inter-regional trade for their economic development, and seaborne trade is the most efficient and economical means of transporting large volume and heavy weight cargoes. Shipping routes are thus described as the arteries of the regional economy.

Through these chokepoints must flow the petroleum and other resources China needs to continue its growth.

However, none of these chokepoints are under Chinese control. Yet.

With the development of it artificial islands in the South China Sea, China is taking steps to be able to control access to that sea. There is an excellent piece by Thomas Shugart at War on the Rocks, China's Artificial Islands Are Bigger (And a Bigger Deal) Than You Think:

But the potential combination of China’s premier anti-ship and anti-air capabilities — along with the sheer, breathtaking scale of China’s island-building — call for serious consideration of the faux islands’ potential impact to U.S. diplomacy and contingency planning, as well as the need to take all possible measures to prevent their full militarization.

Ah, you ask, Why?" The best answer is this graphic from the Shugart article:

 "Range arcs depicting potential coverage of HQ-9 SAMs, YJ-62 ASCMs, and DF-21 ballistic missiles from China’s larger South China Sea island bases."

Should China have malice in their plans, you can seen that bases in the South China Sea give them some degree of control of access to not only the SCS but also threaten access to neighboring countries and limit the sea routes available in the region.

There are currently alternatives:

From "Maritime Economic Interests & the Sea Lines of Communication Through the South. China Sea: The Value of Trade in Southeast Asia," Noer and Gregory (1996)

The cost or re-routing shipping, of course, is time and money. The other cost is the ability of China to force the nations within the range of its weapons to capitulate to China's demands or be cut off from the rest of the world. That might be a little uncomfortable for an old foe like Vietnam. Or for major cities that sit on the ocean:

UN GRID-Arendal graphic

China continues to insist these developments are not martial in nature. It is clear, however, that China is taking steps to protect its sea lines of communication, so China's assertions ought to invoke a "Oh, come on" response from the rest of the world.