I'd go further and say the US government wants "an instrument more powerful than any nuclear weapon" to be built in its territory, by people it has jurisdiction

I'd go further and say the US government wants "an instrument more powerful than any nuclear weapon" to be built in its territory, by people it has jurisdiction over. It might not be a direct US-govt project like the Manhattan Project was, but it doesn't have to. The government has the ties it needs with the heads of all these AI companies, and if it comes to it, the US-govt has the muscle and legal authority to reign control over it. A good deal for everyone involved really. These companies get to make bank and technology that furthers their market dominance, the US-govt gets potentially "Manhattan project"-level pivotal technology— it's elites helping elites.