Here is the impasse definition for academic coursework.
An impasse is defined as a condition or state of conflict in which there is no apparent quick or easy solution
When an impasse exists, the parties are unable to create deals that satisfy their aspirations and expectations
In addition, an impasse can be tactical or genuine. Tactical impasse occurs when parties deliberately refuse to proceed with negotiation as a way to gain leverage or put pressure on the other party to make concessions.
In a genuine impasse, parties feel unable to move forward without sacrificing something crucial.