We Go Together Act This bill requires the President to take certain actions before changing U.S. policy with respect to the U.S.-South Korea Mutual Defense Treaty. Specifically, no later than 120 days before making such a change, the President shall provide to Congress (1) a detailed justification for the change, (2) a certification that the change is in the U.S. national interest, and (3) a certification that an alternative agreement or measure is in place to replace any lost capacity or benefits stemming from the change.