Burma is being brought into the transportation network of China:
The World War II "Stilwell (or Ledo) Road", from northeast India into Burma, is going to be rebuilt. The road was originally, in 1942, built to replace the "Burma Road" that got Allied military aid to Chinese troops fighting the Japanese. But Japan captured Burma in 1942, and cut that connection. The new road will bypass India, and just go from China into Burma. India is not happy about being left out, and nervous about how the new road will go right up to the Indian border.
China is building an oil terminal in Western Burma, where tankers from the Persian Gulf will unload oil, which will then be moved into southwestern China via a new pipeline. China will run the new oil terminal, and the Burmese government will be responsible for the security of the pipeline, which runs through tribal territory that still suffered from periodic violence.
One of China's strategic problems is that they increasingly rely on foreign trade and foreign imports of important raw materials--especially oil. Some analysts speak of China's DF-21 and other anti-access weapons as a means to keep the United States Navy from getting close to China's shores to blockade their ports. But this misses the point that we don't have to blockade China close to China--we can block China's sea trade anywhere along the line of supply. Why station ships off of Shanghai under threat of Chinese military forces when we can station the ship off of Oman and stop an oil shipment at the source?
Burma allows China to shorten their sea line of communication for oil imports from the Middle East and Africa.
China's Hainan Island naval base is also mentioned by analysts as part of the solution to China's trade vulnerability. But even a major base there to project power into the Indian Ocean is too far away from the theater to allow China to sustain a naval challenge to India or America in the Indian Ocean, making even a shortcut through Burma for oil imports less than adequate to secure China's sea line of supply.
So China needs more pieces to secure their sea line of supply. This is where the DF-21 comes in. While a threat to deployed American naval power in the western Pacific, along with other Chinese anti-access weapons, we can adapt to the anti-access weapons. We can change what we deploy in the western Pacific (more subs and smaller ships, and fewer big ships that can be Pearl Harbored the morning of the first day of war; more reliance on our land-based air power in the opening stages of the campaign to clear the way for our big surface ships; more support for Taiwan, South Korea, and Japan in the region to hold the line while we gather our forces; etc.) to adapt to the DF-21 and other anti-access weapons.
But India faces far more problems from the DF-21 than we will, as I wrote here. Based in China, the DF-21 could not help with securing a trans-Indian Ocean supply line even to Burma. Using the technology on longer-range missiles could do the trick, but the obvious solution is to do what the Soviets did before the Cuban Missile Crisis--put their shorter range missiles in range of their targets. Chinese DF-21s based in Burma and supplied through a secure overland route would support a Chinese fleet that sorties from Hainan Island to challenge Indian naval power. And unlike America which has most of its power out of range of China's missiles, India's fleet would be under the gun in home waters.
Add in Chinese anti-ship ballistic missiles in Pakistan (where the Chinese are active in building a potential naval base--alone insufficient to protect the long Chinese supply line but useful in a "string of pearls") to extend China's missile umbrella to the Horn of Africa and China has the ability to support an Indian Ocean campaign to get oil imports to those new pipelines crossing Burma.
India's ability to do more than contain a Chinese base is constrained by a Pakistani army powerful enough to require too much of India's land power to eliminate. That has to be a naval and air campaign to nullify a Chinese base in Pakistan. But Burma is a different matter. Burma's army is large but mostly a police force. India could use their powerful army to take down Burma and deny China the bases that Burma could provide in a war.
Burma could become a launching pad for a Chinese campaign to secure their sea line of communication through the Indian Ocean by smashing India's navy with anti-ship ballistic missiles as the core of the strategy. In the long run, this could also threaten our ability to cut China's Indian Ocean lifeline, but our options to deal with this can afford to focus on the Horn of Africa to cut the supplies from the source farther from China's military assets. India does not have that luxury. But India does have an army otherwise ill-suited to fighting China that could have a decisive impact on a Chinese-Indian naval war.