Donald Trump has said he is looking forward to meeting Kim Jong-un again soon as he thanked the North Korean leader for returning the remains of US soldiers killed in the 1950-1953 Korean war.

“Thank you to Chairman Kim Jong-un for keeping your word & starting the process of sending home the remains of our great and beloved missing fallen! I am not at all surprised that you took this kind action,” the US president tweeted early on Thursday.

“Also, thank you for your nice letter – I look forward to seeing you soon!” Trump added.

The pledge to return the remains of US soldiers was made during the pair’s June meeting in Singapore. North Korea also committed to work towards the complete denuclearisation of the Korean peninsula.

Kim sent a letter to Trump in mid-July saying he hoped there would be a second meeting, but it is unclear if this was the “nice letter” to which Trump referred on Thursday.

Trump also praised an “incredibly beautiful ceremony” in Hawaii, at which the US vice-president, Mike Pence, officially received the remains on US soil.

The pledge to transfer war remains was seen as a goodwill gesture by Kim at the Singapore summit and was the most concrete agreement reached by the two sides.

“I know that President Trump is grateful that Chairman Kim has kept his word, and we see today this tangible progress in our efforts to achieve peace on the Korean peninsula,” said Pence, whose father fought in the Korean war.

More than 7,700 US troops who fought in the Korean war remain unaccounted for. About 5,300 were lost in what is now North Korea.

Other countries under the command of the United Nations also have troops that are still unaccounted for, including the UK, Australia and Canada.

Experts say positively identifying some of the decades-old remains could take decades.

An initial field forensic review indicated the “remains are what North Korea said they were”, said John Byrd, a senior military official, at an air base in South Korea before the remains were flown to Hawaii.