You've lost all credibility with that statement.
There is absolutely no way at this time, to track production and import values outside of the country. The BLS admits this themselves. We do know however, exactly how to calculate output of American manufacturing but like I said, there is absolutely no way to calculate the entire process before output.
. . . even if a company offshores/outsources most of its production process (jobs)to other countries but they still put together the final product here in the USA (they ship back the parts), the Bureau of Labor Statistics counts the entire operation (from start to finish) as manufacturing output.