How do I pause or halt a running campaign?

How do I pause or halt a running campaign?

Hi,
I set up an A/B campaign - and after testing, scheduled the campaign, I noticed an error in the subject line and had to pause or halt the campaign 'mid-flight' - could not find this, and the only option was to delete the entire campaign to halt the send (it was an emergency).

Is there a campaign Pause or Stop function/button? I could not find it - am I missing something?

(Thank you for your help  - I searched the resources and could not find an answer)