TOKYO -- China announced Thursday that it had officially applied to join the Comprehensive and Progressive Agreement for Trans-Pacific Partnership, 300 days after President Xi Jinping first expressed an intent to do so.

But with no concrete outlook for being accepted, why did Beijing make its move now?

Jia Qingguo, a professor and former dean at Peking University's School of International Studies, told Nikkei in November 2020 that a Chinese application would pose a challenge for Japan because "refusing the request would mean a confrontation with China, but Japan cannot accept it easily either because the U.S. would never agree to that."

As a Standing Committee member at the Chinese People's Political Consultative Conference, Jia is deeply involved in making foreign policy.

Three days after the interview, Xi announced at a virtual summit for the Asia-Pacific Economic Cooperation forum that China "will favorably consider joining" the CPTPP. In hindsight, Jia's comments to Nikkei were likely based on the knowledge that such an announcement was coming.

Ever since then-President Donald Trump pulled the U.S. out of the old Trans-Pacific Partnership in 2017, China has weighed joining the trade pact -- which later became the CPTPP -- and has been laying the groundwork. Beijing has spotted a golden opportunity to replace Washington as the leading voice in setting trade rules for the Asia-Pacific region.

Premier Li Keqiang first floated the idea of China joining back in May 2020. This came shortly after Xi's planned state visit to Japan that April was canceled over the pandemic. The Japan trip was extremely important for Beijing amid worsening relations with Washington. China had refrained from expressing interest in the CPTPP until then, understanding that it would push Japan into an awkward position and give Tokyo an excuse to back out of the Xi visit.

But with the trip called off, China was free to act. Once Xi announced interest in November, it was ready to apply anytime.

China does not expect to be admitted soon, given the high standards that the CPTPP requires from members. But Thursday's application cannot be separated from the "China containment" wall Beijing sees being put up.

On Wednesday, the U.S., U.K. and Australia launched a new security grouping, AUKUS, with a heavy focus on China. Washington and London will jointly offer technological support to Canberra to build nuclear-powered submarines. On Thursday, the European Union set out its own "Strategy for Cooperation in the Indo-Pacific" talking of deeper ties with Taiwan.

The CPTPP currently has 11 members, with the U.K. waiting to join. From a purely economic perspective, adding the huge Chinese market to the free trade zone would have a significant impact.

Some members may embrace the idea of having China in the grouping. Such a scenario would be ideal for Beijing.

As Jia predicted, Japan is now in a difficult spot. Turning away China at the door would most certainly trigger some harsh Japan-bashing from the Xi administration. But any lenient position would draw questions from Washington.

Driving a wedge into the U.S.-Japan relationship, the heart of the China containment alliance, appears to be precisely the aim of the CPTPP application.