Nurses, postal workers and railway employees are all walking out this month in the U.K.'s largest series of labor actions in more than a decade. It's a major challenge to Prime Minister Rishi Sunak.

The miners have survived more than 600 days on the picket line, thanks to widespread support and anger at their employer, Warrior Met Coal. Even now, neither side seems ready to budge.

The union representing 1,400 employees at cereal production facilities in four states said the agreement "makes gains and does not include any concessions."