ITAR registration is entity-specific and a change of ownership requires notification to the Directorate of Defense Trade Controls, with advance notice where the transaction involves a foreign person.
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The notification requirements are procedural and well established, but they carry real timing consequences: an acquisition involving foreign ownership triggers a longer process and can involve additional review, and prime customers will not accept shipments from an entity whose registration status is unresolved. The practical steps are to identify early whether any prospective buyer has foreign ownership, to confirm the registration is current and the technology control plan is real rather than nominal, and to schedule the notifications alongside closing rather than after it. Buyers active in defense supply do this routinely; a first-time buyer may not know to, which makes it the seller's advisor's job to raise it.