Washington, Nov 24 (IANS) Prime Minister Manmohan Singh said he was unable to ‘fully understand’ the reasons behind China’s assertiveness over the border dispute with India.

‘We have tried to engage China in the last five years. We have a longstanding border problem with China. We are trying to resolve it through dialogue,’ he said Monday while speaking to policy wonks at the Council on Foreign Relations, the influential US think tank.

Manmohan Singh, who met his Chinese counterpart Wen Jiabao in Thailand this month, added: ‘I have received assurances from the Chinese leadership at the highest level but there is a certain assertiveness on part of the Chinese. I don’t fully understand the reasons for it. That has been a concern.’

Manmohan Singh explained the larger context of Sino-Indian relations, marred by Beijing’s objections to the Tibetan spiritual leader the Dalai Lama’s visit to Arunachal Pradesh and New Delhi’s refusal to prevent him from going to the northeastern state — a region China claims.

The prime minister said the two countries were trying to resolve their border dispute, which led to war in 1962, through dialogue.

‘China is one of our major trading partners. Pending that, both countries have decided to maintain peace and tranquility along the border,’ he said.

This is the first time Manmohan Singh, who has maintained consistently that there was enough space for India and China to grow, has expressed his displeasure over China’s muscle flexing.

Foreign Secretary Nirupama Rao, who is accompanying the prime minister on his visit to the US, told reporters later: ‘Coupled with the rise of China, there is an increased assertiveness on part of China to assert its claims of sovereignty over territory.’

The former Indian envoy to China added that this was very much in evidence during the Olympics, when Beijing made it clear that it would not brook any protests over human rights or Tibet.

Rao added that India was engaged in ‘a good constructive relationship’ with the US, but admitted that there were complex problems like the border dispute that needed to be resolved.

In his address, Manmohan Singh said there was enough space for India and China to grow.

Trying to repudiate any impression of rivalry between India and China, Manmohan Singh underlined that engagement was the best way to promote the peaceful rise of China.

‘We want the world to prepare for the peaceful rise of China as a major power. Engagement is the right path for India as well as the US,’ he said.