Can the Trans-Pacific Partnership be renegotiated after Japan has already ratified it?

The Trans-Pacific Partnership (TPP) has now changed to the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) after the US withdrew. As it currently stands, the trade agreement is between Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam. The agreement, originally signed on 4 February 2016, is being renegotiated after the United States withdrew

According to recent reports “The TPP began as an expansion of the Trans-Pacific Strategic Economic Partnership Agreement (TPSEP or P4) signed by Brunei Darussalam, Chile, New Zealand, and Singapore in 2005. Beginning in 2008, additional countries joined the discussion for a broader agreement: Australia, Canada, Japan, Malaysia, Mexico, Peru, the United States, and Vietnam, bringing the total number of countries participating in the negotiations to twelve. In 2017, the United States withdrew from the agreement. The other 11 TPP countries agreed in May 2017 to revive the deal without US participation.”

The original TPP contained measures to lower both non-tariff and tariff barriers to trade, and establish an investor-state dispute settlement (ISDS) mechanism. Separately, an analysis using an unconventional model by two Tufts University economists found the agreement would adversely affect the signatories. Also, many observers of the negotiations have argued that the trade deal would have functioned in a geopolitical context by reducing the signatory member’s dependence on Chinese trade and bring the signatories closer to the United States.

Twelve countries participated in negotiations for the TPP: the four parties to the 2005 Trans-Pacific Strategic Economic Partnership Agreement and eight additional countries. As it stands, the agreement will enter into force after ratification by all signatories, but if the agreement is not ratified by all before 4 February 2018, it will enter into force after ratification by at least 6 states which together have a GDP of more than 85% of the GDP of all signatories.

The largest economy in the Pacific Rim not yet a member of TPP is China. According to the Brookings Institution in 2013, the most fundamental challenge for the TPP project regarding China was that "it may not constitute a powerful enough enticement to propel China to sign on to these new standards on trade and investment. China so far has reacted by accelerating its own trade initiatives in Asia."

Academic followers of the agreement report that Japan's main competition in the region is China, and the two nations have opposite views on how the South-east Asia's economy should develop. Japan tried to take control by establishing the Asian Monetary Fund (AMF), which the U.S blocked. In 2011 however, Japan managed to establish a cooperative agreement with China and Korea called the "PRC–Japan–Republic of Korea Free trade agreement", also known as the CJK FTA, which did not include the U.S. The consensus is that Japan's intention was that they could use the People's Republic of China issue in order to gain U.S support for backing the TPP, and shift the negotiations toward Japan's agendas.