Didn’t Truman call out the guard on a strike under the pretext that commerce (I believe it was a rail strike) was a matter of national security? I suspect the same rationale could be used for USS and GM....
What did President Truman threaten to do to the striking railroad workers?
How did Truman respond to striking workers in 1946?
As a result, on May 24, 1946, Truman issued an ultimatum declaring that the government would operate the railroads and use the army as strikebreakers.
When the deadline passed, Truman went before Congress to seek the power to deny seniority rights to strikers and to draft strikers into the armed forces.