In about 1952, the "rights of RR unions to strike" was rather severely curtailed by the GOP's influencing Congress to pass restrictive amendments to the RLA which very narrowly defined issues and processes on how self-help (strikes and lock-outs) can be implemented, with the excuse being "national security" because of the Korean War. So there won't be a strike unless it's over an issue subject to wildcatting, which means essentially anything which is not covered by the Agreement.