Westerners' disgust doesn't tackle all the world's powerful rich equally.
Russian billionaires are targeted now, but not the murderous rulers of
Salafi Arabia and the UAE.
Nor do all attacked countries get equal support.
To some extent, the differences in US response reflect the difference
in what options the situations offer.
In Syria, the US tried supporting the rebels against Assad, but they
were inseparable from the intolerant Islamists, eager to persecute
non-Muslims and non-Sunnis.
Only the secularist, socialist Kurds deserved and deserve
support, but they could not offer a potential government for all of Syria,
including those who are not Kurds.
By contrast, in Ukraine it is clear who to support, and that makes it
easy to do so.
The US can stop drone bombings in Yemen, and perhaps take a neutral
stance there, but that won't make its civil war go away.
The US could give less support to the regimes of Salafi Arabia and the
UAE, but barring trying to impose regime change there, which we should
know would cause disaster, it can't deal with those countries except
through those regimes.