while assembling the aircraft in u.s. could circumvent the 300% duties proposed in the cseries dumping petition by boeing, airbus ceo tom enders and bombardier ceo alain bellemare assured that this factor did not drive the partnership, but negotiations began in august after the april 2017 filing and the june decision to proceed and, as a result, boeing was suspicious. leeham news commented that "the airbus-bombardier partnership [...] thrusts a big stick up boeing's tailpipe".