Indian Defence Minister Rajnath Singh told his Chinese counterpart that the two countries should seek a “permanent solution” to their decades-old border dispute, India’s defence ministry said on Friday.

Singh met China’s Dong Jun on the sidelines of the meeting of the defence ministers of the Shanghai Cooperation Organisation (SCO) in Qingdao on Thursday and stressed on solving issues between the two countries through a structured roadmap, the ministry said in a statement.

The world’s two most populous nations — both nuclear powers — share a 3,800-km, largely undemarcated and disputed border in the Himalayas and have gone to war over it.

Although the frontier has been mostly peaceful in recent decades, a deadly clash between their troops in 2020 resulted in the deaths of 20 Indian and four Chinese soldiers.

The clash led to a four-year military standoff with both armies deploying tens of thousands of troops in the mountains until they reached a pact in October to step back, leading to a thaw in ties.

During his meeting with Dong, Singh also called for bridging the trust deficit created after the 2020 standoff, New Delhi said.

The SCO is a 10-nation Eurasian security and political grouping whose members include China, Russia, India, Pakistan, and Iran. Their defence ministers’ meeting was held as a precursor to the annual summit of its leaders set for the autumn.