The surprise trip came after Yoon attended a NATO alliance summit in Lithuania and visited Poland this week, where he expressed solidarity with Ukraine, Reuters reported.
In a press conference, Yoon said South Korea plans to provide "a larger scale of military supplies" to Ukraine this year, following last year's provision of non-lethal supplies such as body armor and helmets. He did not give more details.
Yoon said South Korea also plans to provide Ukraine with $150 million in humanitarian aid this year, following about $100 million in 2022.
Zelenskiy asked Yoon to boost military support when they first met in May. Yoon said on Saturday that South Korea has delivered safety equipment and humanitarian aid that Ukraine needs, since May, including mine detectors.
In 2022, South Korea's arms sales jumped to more than $17 billion from $7.25 billion the year before, including a $13.7 billion arms deal with Poland - Seoul's biggest ever - supplying rocket launchers and fighter jets.
AMK/PR