U.S. President Joe Biden and Chinese leader Xi JinpingAccording to Jake Sullivan, U.S. national defense advisor Jake Sullivan on Tuesday, they agreed in a virtual meeting that would examine the possibility of arm control negotiations.

Biden and Xi agreed to “look to begin to carry forward discussion on strategic stability,” Sullivan said in a reference to U.S. concerns about China’s nuclear and missile buildup.

“You’ll see at many levels an intensification and protection of this competition to prevent it from veering off into conflict,” Sullivan explained in a Brookings Institution webinar.

Sullivan was not specific about the format of discussions regarding strategic stability, but he did say that:

This isn’t the same thing as the Russian context of the formal strategic stabilization dialogue. It is more mature and has a longer history. There’s less maturity to that in the U.S.-China relationship, but the two leaders did discuss these issues and it is now incumbent on us to think about the most productive way to carry it forward.”

Washington has repeatedly urged China to join it and Russia in a new arms control treaty.

Beijing asserts that China’s arsenal is far more extensive than the one of its two neighbors. It says it is ready to conduct bilateral dialogues on strategic security “on the basis of equality and mutual respect.”

It was the two leaders’ most in-depth exchange since Biden took office in January.

They spoke for approximately three-1/2 hours but did little to reduce differences, which has raised the possibility of a conflict between the superpowers.

The United States hoped that the meeting would bring stability to a relationship becoming increasingly strained over various issues. This includes Beijing’s aggression toward Chinese-reclaimed Taiwan.

Asked if there was any progress on tensions over the self-ruled island, Biden said: “Yes. We made very clear we support the Taiwan act and that’s it.

Biden was referring to the Taiwan Relations Act, a U.S. law that requires the United States to provide Taiwan with the means to defend itself, though Washington has long followed a policy of “strategic ambiguity” on whether it would intervene militarily in the event of a Chinese attack.

“I said that they have to decide … Taiwan, not us,” Biden added later. “We don’t encourage independence.”

Xi told Biden in their meeting that China would take “decisive measures” in the event that Taiwan crosses Beijing’s red line in seeking independence.

Sullivan said Xi and Biden discussed a broad range of global economic issues, including how the United States and China can work together to ensure world energy supply and price volatility do not imperil the global economic recovery.

In the meeting Biden pressed his Chinese counterpart on human rights and Xi warned that China would respond to provocations on Taiwan.

A senior U.S. official said in a briefing after the meeting that the U.S. aim was not to ease tensions, nor necessarily was that the result, and there were no breakthroughs to report.

China’s state media quoted unnamed Chinese sources in foreign ministries as saying that the sides would relax restrictions on journalist access from their respective countries.

China Daily reported that a consensus had been reached regarding journalist visas and other issues before the virtual meeting.

A spokesperson for the U.S. State Department gave similar details, saying China had committed to permit U.S. journalists already in the country to depart freely and return, which they had previously been unable to do. According to it, the United States would facilitate similar treatment of Chinese journalists.