you cant not use US miles to upgradee UA flight
Ummm...you sure that's true.
From the US site.
Make your miles go further. Now you can use your Dividend Miles to upgrade on Star Alliance member airlines.
It’s easy to get upgrades. Here’s how:
Book your full-fare Economy or Business class ticket on any participating Star Alliance member airline
Use your miles for your Star Alliance Upgrade Award (you’ll need your confirmation number, flight number and booking class)
Upgrade to Business or First Class
We’ll confirm your upgrade right away if it’s available and automatically deduct the miles from your account. All you’ll need to do is show up to the airport ready to enjoy your Star Alliance upgrade.
ETA:@myb821, I am not trying to be mean, just curious what the whole thing about upgrades is if you can't use their miles for it.