Re: Insecure gear
"National security for the US nowadays is overwhelmingly about economic ascendancy."
Which is increasingly under threat
Quick history lesson: US dollar hegemony has been oil-backed since 1972 by a quid-pro-quo with OPEC countries ("You take payment only in US dollars, we provide 'military protection' in the Middle East") that's allowed massive debt levels to build up (This happened to the pound when it was the hegemonic currency too). Whilst the debt is backed in USD it's inconsequential but if the hegemonic currency falls out of favour then the debts become due (which is what happened to Britain post WW2)
A good chunk of recent US activity over the last 25 years has been squarely aimed at "punishing" oil economies who dared take payments in something other than USD (Venezula, Iraq, Libya) but the tide is inexorable and the Iran/China deal is unignorable.
Add the fact that China actually built and fired up a Molten Salt Fuelled nuclear reactor last month (the kind that the USA built at Oak Ridge in the 1960s, then promptly banned and declared beyond top secret in 1972) and oil's time as the energy course of choice is looking increasingly shaky even if CO2 emissions weren't an issue
TL;DR: This isn't so much about "economic ascendancy" as the overly aggressive 900 pound gorilla realising there are now 5 more 900 pound gorillas in the room (China, EU, India, BRICS, with African Union rising quickly) and pitching a fit because he assumes they're going to beat the crap out of him (projection), so deciding to get a few blows in first.
China spent 2500 years as the world's leading economy and technological leader, only falling behind recently and they did it almost entirely via trade. I'm picking they're taking the long view and Sun Tzu's recommendation that war is a huge waste of resources which is best avoided whereever possible when you can usually defeat your "enemy" by waiting for them to overspend themselves into military oblivion