Experts also said that the condolence message should be interpreted in the context of the friendship the two leaders built through three summits last year and added that it should not mask what the North is really up to as shown by the latest provocations.

"North Korea has apparently made clear its inter-Korean policy, which is to go tough on it until any progress is achieved in its denuclearization talks with the US," Hong Min, a research fellow at the Korea Institute for National Unification, said.

"Kim's condolence message should be contrasted as no more than part of diplomatic courtesy separate from politics and other inter-Korean issues and the subsequent projectile firing seems to be messages aimed at singling to Seoul that it will put inter-Korean relations on hold and strengthening its negotiating leverage against Washington," he added.

Inter-Korean relations improved significantly last year buoyed by summit talks Moon and Kim, held three times in April, May and September. Moon traveled to Pyongyang for the September summit and invited Kim to visit South Korea, though that visit did not materialize.

Since the breakdown of the summit between North Korean leader Kim and US President Donald Trump in February, however, the cross-border ties have remained at a standstill with Pyongyang often complaining that Seoul is not active enough to move their relations forward mindful of global sanctions imposed against it.

North Korea and the US resumed nuclear talks earlier this month in Stockholm but the talks broke down again. The North has doubled down on its criticism of the US and South Korea ever since.

While conducting a series of missile tests since May, the North has stayed almost mum in recent months on South Korea's proposals for dialogue, cooperative projects and even humanitarian assistance.

In July, the North rejected the South's offer to provide rice through an international assistance agency, expressing its displeasure with a joint military drill by Seoul and Washington.

In a recent setback and apparent indication of Pyongyang's frustration with the lack of progress in cross-border projects due to global sanctions, North Korea last week asked South Korea to remove its facilities built for a long-suspended joint tour program to Mount Kumgang on its east coast, saying that it will build its own international tourism zone there.

The decision is a follow up on North Korean leader Kim's directive to destruct all "unpleasant-looking" South Korean facilities there. On Monday, the South offered to hold working-level talks about the issue, but the North turned the proposal down the following day.

Some held out hope that Kim's condolence message to President Moon could serve as a rare chance to create a favorable mood in relations between the two Koreas, given that the North has a history of using funerals of major figures as a means to convey reconciliatory messages.

When former South Korean President Kim Dae-jung, the architect of the sunshine policy of engaging North Korea, died in 2009, then North Korean leader Kim Jong-il sent a condolence message to the bereaved family the next day and sent a delegation of special envoys to the funeral.

For the death of Lee Hee-ho, the wife of late President Kim Dae-jung in June this year, North Korean leader Kim Jong-un had his younger sister, Kim Yo-jong, deliver a condolence message and flowers to the South. That gesture led to eased tensions and resulted in the surprise brief meeting between their leaders at Panmunjom along with US President Donald Trump.

"The fact that Chairman Kim delivered the message in his name despite South Korea not officially informing the North of her death appears to indicate that he is still interested in inter-Korean relations," Yang Moo-jin, a top North Korea expert at the University of North Korean Studies, said.

"It could be seen as a message sent to consol the president but, as evidenced in many historical cases, condolence messages and paying tribute have contributed to improvement in relations between states. I hope that Kim's latest action could bode well for inter-Korean ties going forward," he added.  (Yonhap)