Washington, Sep 18 (IANS): US President Donald Trump once again mocked North Korean leader Kim Jong-Un, calling him "Rocket Man", an allusion to Pyongyang's recent nuclear tests, as well as speaking ironically about the "long ... lines" of people waiting to get fuel in the nation after the sanctions imposed by the UN.

"I spoke with President Moon of South Korea last night. Asked him how Rocket Man is doing. Long gas lines forming in North Korea. Too bad!" wrote Trump on his Twitter account on Sunday.

The reference to the gas lines was made, evidently, as an allusion to the sanctions imposed last week by the international body on North Korea after Pyongyang's recent missile tests, Efe news reported.

The latest sanctions include a reduction in the amount of petroleum that Pyongyang may import, although the true impact on the North Korean economy has not yet been confirmed.

Moon and Trump agreed on the need to fully implement the sanctions so that North Korea understands that continuing with its weapons testing will only result in its increasing diplomatic isolation and additional economic pressure, which will -- in all likelihood -- ultimately lead to the regime's "collapse", the South Korean President's Office said.

The conversation between the two leaders came after Pyongyang's launching on Friday of another long-range missile, which overflew Japanese territory before landing harmlessly in the Pacific.

Moon and Trump agreed to place additional pressure on North Korea, including implementing the new batch of sanctions unanimously adopted by the UN Security Council this past week, a response to Pyongyang's sixth and most power nuclear test on September 3.