While seizing oil supplies and using them to corruptly reward cronies of Trump’s is probably part of it, a bigger part of it is just to have a war, both to provide a legal and propaganda cover for domestic repression (a war with Venezuela —due to a completely fictitious invasion by Venezuela—is already part of the pretext for that since Trump’s invocation of the Alien Enemies Act on that basis in March) and to provide an electoral rally-around-the-flag effect.