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This is the world in brief from The Economist.

Our top stories.

Donald Trump ousted Mike Walts as America's national security advisor and temporarily replaced

him with Marco Rubio, the Secretary of State.

Mr. Walts came under intense media scrutiny

after he mistakenly added the editor of the Atlantic to a chat on Signal,

a messaging app in which officials discussed plans for airstrikes in Yemen.

Mr. Trump said Mr. Walts, quote,

worked hard and nominated him to be America's next UN ambassador.

South Korea's acting president, Han Duk Su, resigned amid reports that he plans to run for a

full presidential term next month.

Meanwhile, the Supreme Court overturned the acquittal of Li Jiameng, the contests frontrunner, over alleged election law violations. South

Korea has been gripped by political turmoil since Yun-Suk Yul, who was recently removed from office,

attempted a failed coup in December.

Ukraine's president, Vladimir Zelensky, called on allies to put further pressure on Russia

to agree to a ceasefire. His comments came after a Russian drone strike on Odessa in southern Ukraine,

killed two people.

...