Cooperation or antagonism: Where will America and China's relationship go from here? That is the question the Group of Twenty summit made us consider.

At the G20 summit in Hangzhou, President Obama met and talked with Xi Jinping, the Chinese head of state.

The conference was the world's last look at a frank discussion between the two leaders during Obama’s tenure. Their talks summarized U.S.-China relations under the Obama administration, and they also drew attention as a forecast of the next presidential era.

It was announced that before the summit, both nations had ratified the Paris Agreement, a series of measures to combat global warming. I can appreciate that America and China, the top two global economic powers, are undertaking measures to combat the global issue of climate change. Obama advocated this as one of the benefits of cooperation, saying, “China and the United States are prepared to show leadership and to lead by example.”

On the other hand, it was clear they disagreed on the field of military defense. The Permanent Court of Arbitration ruled against China's continued military expansion in the South China Sea – a ruling that Obama wanted China to accept. Xi, however, made it clear that he rejected the court's decision.

At the summit, Xi once again expressed his objection to America’s deployment of the Terminal High Altitude Area Defense, or THAAD, missile system in South Korea. Neither country's leader could hide the depth of the gulf between them.

If we look back on Obama's seven and a half years in office, we can see how he has shifted gears. Initially, he sought a way to work with China to address important issues in the world. However, as China has laid bare its heavy-handed means of diplomacy, such as its oceanic military expansion, Obama took up an attitude of vigilance and confrontation.

Will China be a threat to world safety and security from here on out? Or will it fulfill its responsibilities and contribute to the stability of its region? Naturally, China needs to make a rational judgment and choose the path of peaceful coexistence. At the same time, it is vitally important that America guide China toward adopting a framework of international cooperation.

No matter who becomes the next U.S. president, they need to be able to skillfully handle such a tense relationship and remain steadfast in maintaining an open dialogue.