Did sanctions push N Korea into US talks?

Pretty sure the biggest scare was the increasing rehearsals and practice going on for a Military first strike against North Korea, coupled with sanctions, coupled with they have no real friends left in the world. Combination of items, though I would give the most weight to the increasingly realistic training of an incursion from the South by the U.S., South Korea and Japan and the United front they kept up in the face of repeated temptations by the North to split the alliance. And finally both China and Russia finally entering into an agreement to not circumvent sanctions.

North Korea is largely a paper tiger, the only real bargaining chip it has is avoidance of war, which was deteriorating rapidly as the date was approaching for them being able to conduct a realistic launch of a ICBM that could re-enter the atmosphere.

If negotiations move forward and the North denuclearizes completely, it will be the end of the North Korean regime.

No, North Koreas Hydrogen """test""" caused an earthquake that destroyed their nuclear facility. Russia immediately sent units to Vladivostok similar to the response at Chernobyl. The sanction too have an effect but I think it will be years before they are rebuilt.
This is an opportunity, if we get our troops out of the south, they and the North may be able to come to a new accommodation.

You heard me say it before. Having proven successful nuke tests and missile launches also played a role in N. Korea offering talks with S. Korea and then the U.S.