A North Korean official responded that the invitation was “interesting,” and from there, a meeting was quickly arranged.
US-North Korea diplomacy has advanced in fits and starts
Complicating efforts to restart the talks have been a series of short range missile tests conducted by the North Koreans. All of the tests have been non-nuclear, and none of the tested weapons could reach the US, although all had the capability to strike US allies like Japan and South Korea. As said by Alex, the tests were likely a signal to Trump:
This posturing was followed by something of an olive branch, however. In late May, the state run Korean Central News Agency released a scathing assessment of one of Trump’s political rivals, Democratic presidential candidate Joe Biden. The article brought up issues from Biden’s past, and referred to him using unflattering language; at one point, it called the former vice president “a fool of low IQ.”
Both leaders are clearly hopeful their personal relationship can lead to progress, but in order to avoid the sort of failure that happened in Hanoi, diplomats from both the US and North Korea will need to engage in long and careful negotiations. A timeline for those talks has not yet been set.