JOHANNESBURG (Kyodo) -- The Group of 20 countries vowed Saturday at their summit to tackle "unilateral trade measures inconsistent" with World Trade Organization rules, in an apparent challenge to the tariffs imposed by U.S. President Donald Trump, who is not attending the meeting.

With Trump absent and the United States not sending any government officials, the summit took the unusual step of adopting its leaders' declaration at the outset of the meeting. It was then unveiled by South Africa, this year's G20 host.

Trump has repeatedly snubbed the framework as he pursues his "America First" mantra, upending multilateralism, while claiming that white farmers are being abused in South Africa, an allegation that the nation has dismissed.

The declaration, not backed by the United States, also expressed concern over rising "global economic uncertainty and fragmentation," and affirmed that the "threat or use of force to seek territorial acquisition" must be avoided.

"We underscore our belief in multilateral cooperation to collectively address shared challenges," it added.

South Africa, which is chairing a G20 summit for the first time, is seeking cooperation on a number of issues such as climate change and the debt plaguing developing nations.

Japanese Prime Minister Sanae Takaichi, who is attending a summit of the group for the first time, a month after assuming office, hopes to underscore the importance of a rules-based international order and deeper cooperation with developing countries collectively known as the Global South.

Her G20 debut comes amid a deterioration in relations between Japan and China following her recent comments on Taiwan, a self-ruled democratic island that Beijing views as part of its territory.

In South Africa, China is aiming to build a coordinated front with emerging countries to pressure Takaichi to withdraw her parliamentary remarks about Japan's potential involvement in a Taiwan contingency, foreign affairs experts said.

Besides Trump, Russian President Vladimir Putin is absent, at a time when the United States is seeking to broker a cease-fire deal between Russia and Ukraine.

Chinese President Xi Jinping is also skipping the gathering, with Premier Li Qiang attending instead. China has said Li has no plans to meet with Takaichi on the sidelines and whether there is a brief exchange between the two will be closely watched.

During their talks Saturday, Li agreed with South African President Cyril Ramaphosa that their countries would support each other on issues concerning their core interests, with Taiwan in mind, China's Foreign Ministry said, in an apparent counter to Takaichi.

During a G20 session the same day, Takaichi, a pro-Taiwan lawmaker, referring to frequent conflicts worldwide and uncertainty surrounding the global economic outlook, said the international community is facing a complex set of crises.

G20 leaders have issued joint declarations ever since its inaugural summit in Washington in 2008 at the height of the global financial crisis, even during Trump's first presidential term from 2017.

The G20 summit in South Africa is the first since Trump's return to the White House at the start of 2025 and his barrage of higher import tariffs, which have raised concerns about the global economy and free trade.

The International Monetary Fund has projected global economic growth of 3.2 percent this year, below the average of 3.7 percent prior to the COVID-19 pandemic, while warning of high uncertainty due in large part to the impact of Trump's tariffs.

Shortly before departing for Johannesburg, Takaichi's government finalized a massive economic package to ease the pain of rising prices on households and the blow from higher U.S. tariffs, while boosting long-term growth through strategic investment. But her push for more fiscal spending has weakened the yen and sent Japanese government bond yields higher.

The dispute with Beijing is already threatening to hurt economic growth, with China suspending imports of Japanese seafood again after Takaichi said a military attack on Taiwan could present a "survival-threatening situation" for Japan, indicating a potential response involving its Self-Defense Forces.

The G20 groups Argentina, Australia, Brazil, Britain, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United States, the African Union and the European Union.

Trump is set to chair next year's G20 summit at his golf resort in Miami, Florida, the state that is also home to his Mar-a-Lago estate.