Facebook CEO Mark Zuckerberg's Chinese is so good, he didn't speak a word of English with Chinese President Xi Jinping

Facebook CEO Mark Zuckerberg's Chinese seems to be getting better by the day.

In fact, it's getting so good, he spoke entirely in Chinese during his meeting with President Xi Jinping of China on Wednesday.

"Today I met President Xi Jinping of China at the 8th annual US-China Internet Industry Forum in Seattle," Zuckerberg wrote on his Facebook wall.

"On a personal note, this was the first time I've ever spoken with a world leader entirely in a foreign language. I consider that a meaningful personal milestone. It was an honor to meet President Xi and other leaders."

This isn't the first time Zuckerberg showed off his Chinese fluency in public. Last year, he conducted his entire 30-minute Q&A at Tsinghua University in China in Mandarin. On the Chinese Lunar New Year, he also shared a video in which he speaks in Chinese.

There's a few reasons for Zuckerberg putting so much effort into learning Chinese. His wife's family speaks Chinese, and it also helps him understand Chinese culture, a market Facebook may eventually want to get into. Facebook is currently blocked in China, as are other popular websites such as Google and YouTube.

The meeting on Wednesday was put together as part of President Xi's visit to the US. Some of the most powerful tech leaders, including Amazon CEO Jeff Bezos, Apple CEO Tim Cook, and Microsoft CEO Satya Nadella were all in attendance to meet the Chinese head of state.

Here's a group photo of the meeting: