South Korea’s presidential office has kept mum on North Korea’s latest mockery of its efforts to facilitate nuclear talks between Washington and Pyongyang.

On Saturday, Kim Kye-gwan, Pyongyang’s former nuclear envoy, took issue with an earlier announcement by the South’s top security official that Seoul had conveyed US President Donald Trump’s birthday message to North Korean leader Kim Jong-un.

Returning from a trip to Washington on Friday, Chung Eui-yong, director of the National Security Office, told reporters that Trump had asked President Moon Jae-in to deliver a congratulatory message to Kim.

The former North Korean nuclear envoy, who is currently a Foreign Ministry adviser, said in a statement that it was “somewhat presumptuous” for Moon to meddle in the personal relationship between Trump and Kim.

He said Pyongyang had earlier received a personal letter from Trump on the occasion of Kim’s birthday on Jan. 8, adding that Seoul seems unaware that there is a special liaison channel between the US and North Korean leaders.

His statement came as Seoul has been waiting for Pyongyang’s response to Moon’s overtures to improve inter-Korean relations in his New Year’s address. Moon proposed that the two Koreas make concerted efforts to create the conditions for Kim to visit the South as earlier agreed between them. He also reaffirmed his commitment to push for the resumption of two major inter-Korean projects -- the Kaesong industrial park and Kumgangsan tours -- as well as the reconnection of roads and railways across the border.

The North seems to have no interest in Moon’s proposals.

It has apparently judged that the Moon administration will be unable to violate US-led international sanctions in order to carry forward the cross-border projects. Without substantial rewards, Kim would not be inclined to visit Seoul.

In fact, Pyongyang has ridiculed Seoul’s efforts to act as a mediator between the US and the North over the past year, as it sees no possibility of the Moon government stepping out of line with Washington to resume inter-Korean economic cooperation.

In his New Year’s Day message, North Korean leader Kim warned of a “new strategic weapon” test and “shocking actual action” to increase pressure on the US to make concessions in the stalled nuclear negotiations.

The North is likely to refrain from ending its self-declared moratorium on nuclear and long-range missile tests, as it is hard to predict Trump’s response to what he would no doubt see as a provocation that harmed US security interests and his own reelection prospects. Trump’s impromptu decision to order the killing of a key Iranian general last week may have added to the Kim regime’s concerns about the erratic US leader.

Pyongyang now seems to be bracing for a protracted standoff with Washington, which could allow it to further enhance its nuclear and missile capabilities. It may seek to use its increased arsenal to demand that negotiations with the US focus on mutual reduction in nuclear arms rather than its denuclearization.

The statement from the former North Korean nuclear envoy said dialogue with the US could resume only when it fully accepted Pyongyang’s demands.

North Korean state media’s repeated calls for self-reliance seem to suggest Pyongyang is preparing for a prolonged stalemate in the nuclear talks.

On Monday, the organ of the North’s ruling party emphasized the need to grow manufacturing and other major industries in a “self-reliant” manner to better fight “murderous” sanctions against the totalitarian state.

At this crucial juncture in the process of Pyongyang’s denuclearization, the Moon government should be in step with Washington to tighten sanctions on the Kim regime.

It would be inappropriate for Seoul to seek to expand room to maneuver in carrying forward inter-Korean projects when Pyongyang clings to its nuclear arsenal. Doing so would only deepen US concerns that the Moon administration is overly eager to promote inter-Korean cooperation in the absence of progress on the North’s denuclearization.

In fact, it might be impossible for Seoul to push for joint projects with the North in a significant manner despite objections from the US.

Inter-Korean cooperation needs to be enhanced in tandem with substantial steps toward dismantling the North’s nuclear arsenal.

The Moon administration appears particularly eager to welcome Kim to Seoul ahead of April’s general election in a bid to influence voter sentiment in favor of the ruling party.

But further attempts to court the North without being in touch with reality would only invite more mockery from Pyongyang.