Japanese Prime Minister Shinzo Abe spoke after attending a weekend meeting of Asia-Pacific leaders in Peru at which some said they might seek to modify the 12-nation TPP pact to make it more appealing to US-President-elect Donald Trump, who has strongly criticised it, or seek to implement it without the US.
But Abe discounted the idea of going ahead without American participation.
"TPP is meaningless without the United States," he said at a news conference during his official visit to Argentina.
He also said the pact couldn't be renegotiated. "This would disturb the fundamental balance of benefits."
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As Japan's most powerful leader in a decade, Abe had invested political capital in overcoming strong domestic opposition to the TPP, which Trump called "a disaster for jobs" in the United States.
Abe and the other 20 leaders of the Asia-Pacific Economic Cooperation group closed their annual summit Sunday with a unified call to resist the protectionist sentiment highlighted by Trump's victory and Britain's vote to leave the European Union.
The Japanese leader declined to comment on possible policies of the incoming Trump administration.
Last week, he became the first world leader to meet with Trump since his election. Abe, who was seeking reassurances over the future of US-Japan security and trade relations, described the meeting as "really, really cordial," but he offered few details of their discussion.
There are growing concerns in Japan that Trump might follow up his campaign rhetoric and demand that Tokyo pay more for the 50,000 American troops stationed in Japan under a security treaty. Japan pays about $2 billion a year, about half of the non-personnel costs of stationing the US troops, while South Korea pays about $860 million a year for about 28,000 American troops based there.
Japan's pacifist constitution, drafted under US direction after World War II, forbids the use of force in settling international disputes, but the government has reinterpreted the constitution to allow Japanese troops to use force in some situations.
For the first time since World War II, Japanese peacekeepers arrived in South Sudan on Monday with a mandate allowing them to use force to protect civilians.
Earlier Monday, Abe met with Argentine President Mauricio Macri and signed trade deals in the first visit by a Japanese premier to Argentina in 57 years. Abe was joined by business leaders and CEOs of major Japanese companies and banks, including Mitsubishi, Bank of Tokyo and Toyota.
"From here on, through the joint public and private sectors, we will promote Japanese involvement in infrastructure and other sectors in Argentina," Abe said, praising the huge potential of South America's second-largest economy and Macri's efforts "to encourage free and open economic policies."
Business-friendly Macri has promised to revive Argentina's weak economy after 12 years of protectionist policies under his predecessors. Since taking office in December, Macri has focused on attracting foreign investors, cutting government spending and ending economic distortions. But some industries are still struggling and Argentines continue to lose purchasing power to one of the world's highest inflation rates.
Abe also said that he had discussed the importance of world peace and stability with Macri and agreed with him on the "importance of solving conflicts peacefully."
"We've also exchanged opinions about the need to pressure North Korea more because the nuclear missile threat from that country has increased," Abe said.
Abe has urged an expanded role for Japan's military so that it can respond to threats that include China's growing military assertiveness and North Korea's nuclear ambitions, and he hopes to eventually rewrite the pacifist constitution.
Many in Japan oppose such constitutional amendments.
