One of the major reasons of tension between India and China is the border dispute surrounding Arunachal Pradesh. There is another region named Aksai Chin that is part of this border dispute as well. Arunachal Pradesh is a part of India while Aksai Chin is a part of China. The geographical conditions in both these regions are such that they work in favour of the present arrangement. Both the countries lay claim to the aforementioned regions and their immense respective nuclear capabilities mean that maintaining the status quo is the only option that they have. In fact, the border dispute is one supposed to be one major reason behind the invasion of India by China in 1962.
The Masood Azhar issue
Masood Azhar is the founder and leader of Jaish-e-Mohammed, an Islamic militant group that is highly active in Pakistan occupied Kashmir. The group has been listed as a terrorist entity in UN as well as in India where it has carried out 2008 Mumbai Attacks and 2016 Pathankot Attack, following which Azhar was taken into protective custody by Pakistan Government. India has tried to get Azhar blacklisted by UN but it has always encountered a roadblock in the shape of China.
China has also been opposed to India’s entry in Nuclear Suppliers Group (NSG) that contains 48 countries in all. In fact China has stated clearly that it is opposed to the entry of any country like India that has not signed Nuclear Non-Proliferation Treaty (NPT) in said group. Beijing has stated that signing NPT should be a mandatory obligation in order for a country to become a part of a group like NSG. China, interestingly though, has asked Pakistan to apply and become an NSG member in spite of it being a non-signatory to NPT.
Dalai Lama issue
Dalai Lama is originally from Tibet, which is a part of China now. He escaped from there when Tibet was taken over by China, sought refuge in India, and was granted refuge as well. Ever since then, he has been running Tibetan Government-in-exile over here. As a country, China is highly sensitive about its territorial integrity and sovereignty and thus it can be understood as to how irritated it would be with Dalai Lama’s government over here. In fact, a lot of people also say that this was what caused the first war between the countries.
Indian Ocean issue
China wants to be a dominant force in Indian Ocean. China has adopted a strategy named String of Pearls whereby it has set up bases all across the area, where India and the US maintain naval bases as well. In fact, a number of India’s bases in the area are surrounded by those of China and India is afraid that this is a major containment strategy by its northeastern neighbours. This is why the government has been spending a significant amount of energy in making sure that this can be prevented from happening. As part of that it is trying to pull Sri Lanka, Maldives, Myanmar, and Bangladesh within India’s sphere of influence.