WASHINGTON (AP) — The U.S. and China said Wednesday they are stepping up cooperation on preserving the ocean and combating illegal fishing despite their differences on maritime security.

Secretary of State John Kerry said that indicates the two nations are "working hard to address differences and to find the areas of commonality."

The two governments discussed ocean policy on the final day Wednesday of high-level talks on security and the economy. The leaders of the Chinese delegation met later Wednesday at the White House with President Barack Obama, who will host China's President Xi Jinping in the fall.

This week's talks are a prelude to Xi's visit, his first to the U.S. since 2013. Despite growing tensions over cybertheft and China's island-building in the disputed South China Sea, the U.S. and China are stressing how they can work together on less contentious issues, such as climate change.

State Councilor Yang Jiechi said they have "broad common interests in global maritime governance" and that they could jointly build a "peaceful and tranquil" marine environment.

Kerry said they would expand cooperation among coast guard and law enforcement authorities to uphold international standards. He did not provide details.

Kerry said one-third of the world's fisheries are overfished, and levels of plastic and pollution are reaching alarming levels, threatening marine mammals and fish. Kerry also warned that the causes of climate change can also cause ocean acidification, which could lead to "ecosystem collapse."

"On the marine environment, there's an urgent need for our countries to step up and help lead," Kerry said.

On Tuesday, Kerry spoke of the need to "reduce tensions rather than add to them" in the South and East China Seas, where China's assertive behavior and land reclamation to advance its territorial claims have rattled its Asian neighbors, U.S. allies among them. China says the disputed areas are its sovereign territory.

Washington took the unusual step last month of publicizing a U.S. military surveillance flight that showed the massive scale of China's island-building, which critics also say is damaging to the marine environment.