U.S. National Security Advisor Jake Sullivan held talks on Monday with China's top diplomat Yang Jiechi to discuss various issues including North Korea and the Russian invasion of Ukraine.

Sullivan had a seven-hour meeting in Rome, Italy with Yang, Chinese Communist Party Politburo member and director of the Office of the Foreign Affairs Commission.

A senior Biden administration official told a press briefing on Monday that the U.S. has serious concerns about the recent escalatory actions from North Korea.

The official said Sullivan was clear with Director Yang not only about those concerns, but also about the steps necessary at this moment and the work that the U.S. hopes to be able to engage with China on.

The official also said the U.S. and China had cooperated in the past to resolve the North Korean issue and the U.S. is closely cooperating with South Korea and Japan as well.

The senior official added U.S. Special Representative for North Korea Sung Kim will meet his Chinese counterpart Liu Xiaoming in the near future to discuss detailed measures on the matter.

The official also expressed "deep concerns about China’s alignment with Russia at this time," adding that Sullivan was direct about those concerns and the potential consequences of "certain actions."