Direct responses
Although Trump and Kim had never officially met until June 12, both leaders have paid close attention to each other's remarks, and have engaged in several exchanges over the last 18 months.
Nuclear programme and sanctions
Under the leadership of Kim Jong Un, North Korea pushed ahead with its nuclear weapons programme and drastically increased ballistic missile testing. North Korea claimed to have successfully tested a hydrogen bomb in 2017 as well as launched its first intercontinental ballistic missile (ICBM).
To counter the threat, multiple rounds of U.S.-led sanctions were approved at the U.N. Security Council in 2017..
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