North and South Korea signaled a surprise thaw in relations on Tuesday, announcing the restoration of cross-border communications that were severed more than a year ago and an agreement between their two leaders to improve ties.

The joint announcement, which coincided with the anniversary of the end of the Korean War, was the first positive development since a series of summits between the North’s leader Kim Jong-un and the South’s President Moon Jae-in in 2018 failed to achieve any significant breakthrough.

The two sides revealed that Kim and Moon had exchanged a series of letters since April in which they agreed that reestablishing hotlines would be a productive first step in rebooting relations between the two countries who, despite the end of their 1950-53 conflict, remain technically at war.