At the 23rd meeting of the Shanghai Cooperation Organisation (SCO) in Islamabad, Pakistan, something unusual caught people’s attention. Two important leaders were there: Iran’s First Vice President Mohammad-Reza Aref and India’s Minister of External Affairs Subrahmanyam Jaishankar. But there was one big question—why wasn’t India’s Prime Minister Narendra Modi present?

To understand why, we need to look at the bigger picture. Relations between India and Pakistan have been strained for a l...