Mediated by Qatar and Pakistan, the talks come as Trump says Iran's denuclearization is 'moving along well' and Tehran warns it will respond 'immediately and powerfully' to threats

Key US-Iran negotiations restart in Qatar on Tuesday, easing immediate tensions while raising questions over nuclear commitments and sanctions relief.

Mediators have established communications channels to de-escalate any incidents, and technical talks are set to continue, the source, with knowledge of the discussions, added.