According to the BBC:
On 22 February, a group of 10 assailants reportedly broke into the building, tying up, beating and interrogating eight people inside.
The incident took place just days before a key summit between US President Donald Trump and North Korean leader Kim Jong-un.
And now there are reports US intelligence services were involved.
Have the North Koreans released any public statement on this alleged attack, for example via international media or via their own state television?