North Korea has dropped insulting messages about US President Donald Trump over the South Korean capital, Seoul.

The fliers were stuffed into balloons and contained notes branding the US president as “mentally ill” and a “dotard,” meaning someone who is weak or senile.

The insults appear to be Kim Jong-un’s response to comments delivered by Trump to the UN General Assembly last month in which the US president referred to the North Korean leader as a “rocket man.”

Pictures of the fliers were posted on Twitter by James Pearson, the North Korea correspondent for Reuters.

“Mentally ill”, “Dotard Trump” - found more propaganda fliers from North Korea in central Seoul. pic.twitter.com/XGZgxdWfFU — James Pearson (@pearswick) October 29, 2017

The messages follow another propaganda drop earlier this month, when posters bearing ghoulish depictions of Trump and South Korean President Moon Jae-in were sent over the demilitarized zone. Another shows Trump being stamped on by a North Korean soldier.

Tensions on the Korean peninsula have been steadily rising as Pyongyang continues to conduct nuclear and missile tests in response to regular joint military drills by the US and South Korea; and in defiance of UN Security Council resolutions.

During a visit to South Korea Saturday, US Defence Secretary James Mattis said he “cannot imagine” the US ever accepting North Korea as a nuclear state. Following a meeting with his South Korean counterpart, Song Young-moo, Mattis said Washington would not relieve the pressure on Seoul’s northern neighbour.

“Make no mistake – any attack on the United States, or our allies, will be defeated. And any use of nuclear weapons will be met with a massive military response that is both effective and overwhelming,” Mattis said.

READ MORE: US Defense chief Mattis ‘cannot imagine’ Washington accepting nuclear Pyongyang

With Washington and Pyongyang amplifying their threats, Russian President Vladimir Putin cautioned in September that “ramping up military hysteria in such conditions is senseless,” and could in fact could lead to “a global, planetary catastrophe and a huge loss of human life.”