Here is a gap that can't be sustained. This chart shows brent crude at new highs while the ruble (inverted USD/RUB here) and Russian stocks sink.
Either Russia will invade Ukraine or it won't. If war starts Russian assets are off limits until we find out what the sanctions are. I don't believe they'll sanction oil & gas or kick Russia out of SWIFT because Europe needs to continue to buy what Russia is selling but that's a tough bet when bullets are flying.
The real opportunity is if there is no war.
Since the talk of an attack has picked up, a huge divergence has opened up between the ruble, Russian stocks and oil. Crude has surged while the world's largest exporter of crude has seen its currency and stock market sink. If there's no fighting, there will be a big rally in the ruble as it catches up to the oil cashflows and Russian stocks (shown via the RSX ETF here) will jump.
Now keep in mind that oil prices should come down as well, so they might meet in the middle but it's a trade to keep in mind if Russia demobilizes.