A naval arms race in the 1920s grew ugly enough that commentators on both sides of the Atlantic were claiming war “not unthinkable.”
This quote is from a lecture by an academic called John Moser; he doesn't give any more details though.
Who were these commentators? How serious was the threat of war, and what if any were the disputes other than naval supremacy? Someone suggested it was over a refusal to pay back Britain's WW1 debt. Wikipedia's article on Britain's national debt mentions some irregularities there, but doesn't say it was serious enough that people thought about war.