"If at a crucial moment such as this, they are used for the umpteenth time, deliberately, expressions that excite the atmosphere, then it is really a question of the senility of an old recidivist bacucco"
The expression "at a crucial moment" refers to the attempts that North Korea and the United States have been making for over a year to relax bilateral relations and find a solution for the so-called "denuclearization" of North Korean territory. Recently the negotiations have entered a deadlock and North Korea has started testing short-range ballistic missiles again, provoking criticism from the US government.
Choe's words were much talked about because it was a long time since the North Korean regime was openly critical of Donald Trump, who in turn had used words of friendship with Kim Jong-un in the past. It is not even the first time that North Korea defines "old bacucco" Trump: it had already happened in 2017.