Global market. The 10% we buy from they will be sold to someone else and we will buy from someone else. There is no change to the market. If the world would agree to enact the tariff then it would work but never going to happen.
China signed on the Iran sanctions under Obama. I actually think the Chinese would be happy to sanction Russia if America would treat them with respect and didn't think we're just looking for an excuse to destroy them so their economy doesn't overtake us. China is much more concerned with a rule based international order and access to Europe through the FSU than the US is with 30%+ of GDP from war equipment
...but sanctions need to remain in place.
There is a difference between hitting a child to teach them a lesson, or beating someone up so he doesn't start a fight again, and completely crushing somebody to the floor. It seems universally accepted there is no chance Russia will back down now, and the only hope is that Putin will be removed, but no sanctions or war have ever accomplished that.
I am watching the news and they say gas might hit $5/gal. I would use a stronger word than might.
They'll just drop the 20% federal excise tax, and then subsidize it if needed. We just print as much as we want anyways