The fourth NSS is the last of Obama's tenure and the president has high expectations for it as he seeks to burnish his political legacy.

Although this summit cannot conclusively settle nuclear security problems, it offers an opportunity for heads of state to reinforce the consensus on preventing nuclear threats. Achievements are expected in terms of management of nuclear facilities, nonproliferation of nuclear weapons and preventing nuclear disasters.

Noticeably, the first Xi-Obama summit this year will take place on the NSS platform as Xi joined global leaders in Washington on Thursday.

China-US relations have been in a subtle state in recent months. Despite restraint from both sides over cyber-security, the two have recently witnessed mounting frictions over the South China Sea, human rights and trade.

The Obama administration has been dangerously testing China's bottom line in the South China Sea. A few weeks ago, the US and 11 other Western countries poured their banal criticisms on China's human rights record. The US has also repeatedly taken measures against Chinese firms ranging from steel to telecom attempting to expand overseas in recent months.

How the two will coordinate their stance over these confrontational issues and whether subtle changes will take place deserve our attention.

There has been both competition and cooperation in the most important bilateral relationship in the world. An underlying principle for China to handle relations with the US is to make cooperation exceed competition.

Therefore, it's of great importance for the two countries to tap as many as possible new opportunities for cooperation. There is a lot of room for China and the US to cooperate in regional hotspot issues including the North Korea nuclear conundrum, the implementation of the Iranian nuclear pact, the security dilemma in Afghanistan, and the Syria crisis. There could also be new cooperation in global governance, including nuclear security, climate change, refugee management, new energy development and poverty alleviation.

The two should also jointly advance sealing the negotiations of a Bilateral Investment Treaty.

Before Obama leaves office, the NSS is the most important event that can put a gloss on his legacy. As the first summit between top Chinese and US leaders this year, the meeting on NSS will set the tune for future Sino-US relationship.

The article was compiled by Global Times reporter Yu Jincui based on an interview with Jin Canrong, deputy dean of the School of International Studies, Renmin University of China. yujincui@globaltimes.com.cn