North Korea could consider a change of approach if the US maintains its sanctions on the nuclear-armed country, leader Kim Jong-un has warned in his New Year speech, after 12 months of diplomatic rapprochement.
"If the US does not keep its promise made in front of the whole world... and insists on sanctions and pressures on our republic," Mr Kim said, "we may be left with no choice but to consider a new way to safeguard our sovereignty and interests".
Mr Kim was referring to his summit with US President Donald Trump in Singapore in June, when he said he had "fruitful talks" and "exchanged constructive ideas".
At the time the two leaders signed a vaguely worded pledge on denuclearisation of the Korean peninsula, but progress has since stalled with the sides arguing over what that means.
The North is subject to multiple sets of United Nations Security Council sanctions over banned nuclear and ballistic missile weapons programmes, which have seen it carry out six atomic tests and launch rockets capable of reaching the US mainland.
"I am ready to sit with the US president again at any time in the future and will make efforts by all means to produce a result that will be welcomed by the international community," Mr Kim said in his address, broadcast by the North's state television.
The leader's New Year speech is a key moment in the North Korean political calendar, reviewing the past and setting out goals for the future.
The 2018 address was a crucial catalyst for the developments that followed.
It came after a year of high tensions when the North made rapid progress in its weapons programmes and fears of conflict rose.
The two leaders traded personal insults - Mr Trump mocked Kim as "Little Rocket Man", who in turn called him a "mentally deranged US dotard" - and threats of war.
On 1 January 2018 Mr Kim ordered mass production of missiles and bombs and warned the whole US mainland was "within the range of our nuclear strike and the nuclear button is on my office desk all the time".
But he also offered to send a team to the forthcoming Winter Olympics in the South - opening the way for the South's dovish President Moon Jae-In to play the role of peace-broker.
A rapid sequence of developments followed, with athletes and a senior delegation led by his powerful sister going to the Pyeongchang Games in February, before Kim met Chinese President Xi Jinping in Beijing ahead of the Singapore summit with Mr Trump.
Mr Kim also met with President Moon three times last year - twice at the border truce village of Panmunjom and once in the North's capital Pyongyang - and at the weekend vowed to meet Mr Moon "frequently" this year.
In his speech, Mr Kim said the US and South Korea should no longer carry out joint military exercises - which have been largely halted since the Singapore meeting - calling such drills "a source of tension".
"War-related equipment - including strategic assets of outside powers - should no longer be allowed to be brought in," he added.
South Korea and the US are in a security alliance and the US stations 28,500 troops in the South to protect it against its neighbour, which invaded in 1950.
