Several years ago, there was a story about Wagyu cattle being "smuggled" out of Japan, which read like a script from a James Bond movie. I can't find any link to the article, so I'll try to reconstruct the essence from memory.
The story was that a U.S. Air Force general was close friends with a high ranking Japanese official. Also, apparently, Wagyu cattle (and real wasabe) are regarded jealously as national treasures, with exporting of cattle (and whatever type of wasabe "seeding" is necessary to reproduce) against the law. In a way, this is similar to the silk worm export prohibitions of a couple centuries ago.
Anyhow, the intrigue involved a half dozen or so Wagyu cattle being secretly procured and loaded onto an air force jet, and shipped to the U.S. I believe this supposedly occurred in the late 70's or early '80's, but the dates are just a guess now.
The number of cattle weren't enough to start a 100% Wagyu breeding herd, so they had to be cross bred with existing cattle of a certain breed, with the goal of attempting to keep each generation at least 80% or so Wagyu stock. This supposedly started in Washington state, with another breeding operation starting in Texas once there were enough hybrids to make that feasible.
So, apparently, there are cattle being raised in this country which have large amounts of Wagyu genetics, but not 100% pure.
(As far as wasabe is concerned, apparently a similar "smuggling" effort was successful, with real wasabe being raised in Oregon.) Kobe steaks or burgers served in this country, probably come from these cattle to a large extent.