Sentence:  In his <WSD>submission</WSD> to the UN, [Christof] Heyns points to the experience of drones. Unmanned aerial vehicles were intended initially only for surveillance, and their use for offensive purposes was prohibited, yet once strategists realised their perceived advantages as a means of carrying out targeted killings, all objections were swept out of the way. 
Meaning of the word marked with <WSD> tags:  The thing which has been submitted.