HONG KONG — President Trump’s tweet Tuesday taunting the North Korean leader Kim Jong-un over the relative strength of the two nations’ nuclear arsenals set off a torrent of concern on Twitter — and a few jokes about masculine preoccupation with size.

Noting that North Korea’s leader, Kim Jong-un, had claimed that a “Nuclear Button is on his desk at all times,” Mr. Trump tweeted that he had his own such button, one that was “much bigger & more powerful.”