At least, in terms of arms sales. The American share of the market in 2008, according the the Congressional Research Service, was 68.4 percent. Italy was number 2 with 6.7 percent, and Russia number 3 with a drop to $3.5 billion in sales, which is a little less than Italy.
There are advantages to doing this, of course. Increased production lowers unit cost, keeps production lines open without a direct payment from American taxpayers, and can foster dependency on the US for spare parts and maintenance.
Personally, I think we’re underestimating the people we sell to. Iran arranged to keep their American planes flying for a long time after the fall of the shah. Israel helped to develop some of the things we sell ,for gosh sake. There are smart people around the world who might pick up the slack for a client dropped by the US.