Definition of "firebreak"

That policy could consist of a statement that the declaring nation would not be the first to use nuclear weapons. This would strengthen the firebreak between the use of conventional and nuclear weapons.

1984, Dietrich Schroeer, Science, Technology and the Nuclear Arms Race, page 293

First, it serves to demonstrate that the practice of sustainable critique […] need not be impossibly philosophically rarefied […] Second, it serves as a firebreak against the unrelieved negativity that, it is sometimes charged, follows from Adorno's practices of reflexivity.

2012, Daniel Levine, Recovering International Relations: The Promise of Sustainable Critique, page 112