The world's three largest arms importers — India, China, and Pakistan — all share borders with one another, some of which are in dispute. These disagreements have occasionally led to armed conflict, like the ongoing dispute over the status of Kashmir, and the 1962 Sino-Indian war.

These disputes, and a host of other regional factors, are fueling the world's biggest conventional arms race. The crosshatched sections on the map denote border disputes. Jeremy Bender

India is currently the world's largest arms importer. According to the Stockholm International Peace Research Institute, its weapons imports rose by 111% between the 2004-2008 and the 2009-2013 periods.

From 2009 to 2013, India accounted for 14% of all international arms imports.

India's weapons imports are almost three times larger than that of its neighbors and rivals, Pakistan and China. China and Pakistan each account for an additional 5% of global arms imports. Notably, Pakistan receives 54% of its arms from China.

India likely feels the need to arm itself in light of some of the long-simmering tensions it shares with its neighbors. India and Pakistan have taken steps to increase dialogue in recent years. But they have been at each other's throats for almost their entire history as independent nations over the undecided status of Kashmir. The unsettled border has played a large part in the three wars India and Pakistan have so far fought. Subsets of the Pakistani government also support militants who have launched terrorist attacks inside of India, like the deadly 2008 assault on Mumbai.

India's relationship with China is also rocky. The two fought a brief border war in 1962 that China decisively won. Despite the outcome, the two countries continue to lay competing claims over the Indian Himalayan province of Arunachal Pradesh, which China calls South Tibet.

India and China are perhaps natural rivals — emerging superpowers that are right on each other's doorsteps. But India feels specifically threatened by a growing Chinese military presence throughout the Indian Ocean region. China has invested in military installations in Pakistan, Bangladesh, Sri Lanka, and Myanmar. Indian General Deepak Kapoor, a former Chief of Staff of the Armed Forces, has referred to these installations as China's "string of pearls" surrounding India.

India receives 75% of its arms imports from Russia. These imports in the 2009 to 2013 period have included a nuclear-powered submarine, 90 Su-30 MKI combat aircraft, an aircraft carrier, and 27 MiG-29K jets for use on that aircraft carrier. India is also a partner in Russia's development of a fifth-generation aircraft, the T-50.