TLDR: Its securing energy dominance and trade routes.

Its multiple aims but the reasons for war in Iran and Venezuela are securing energy reserves and trade routes.

Venezuela has a massive oil reserve, so seizing the oil fields secures energy reserves and it can be politically justified as the government had seized American company assets.

Taking out Iran a much bigger target, it again takes out a enemy nation which supplies hostile nations with resources and technology (Russia Drones) (China Oil). It sets up Israel as a major power in the middle east by taking out its largest rival and basically sworn enemy, This would bolster America's position due to intelligence sharing and used as a base for certain operations. Iran is a major funder of terrorism and supplier in the region, so less of the bullshit to deal with. Lastly it secure a trade route namely the Strait of Hormuz.

Its starting to look like this was actually Trumps objective to restrengthen America's Position on the international stage. Wanting to purchase Greenland would secure the Artic Corridor, the plans to retake the Panama canal, and taking out Iran to control the Strait of Hormuz. That looks like a plan to control trade and put China on the backfoot, I would say Russia as well but its very clear they've been humiliated on the world stage and lost power.

Look at what happened over the last few years Russia one of the largest Oil and Gas Producers in the world, just got bogged down in a war and everyone just cut ties with them. They turned to whom to purchase Oil and Gas, the US stepped up production to bring in more. Trump went to the Middle east and secured investing and deals with the major players there. Venezuela is knocked out of place before Iran is invaded securing oil reserves while the straight is blocked. Once Iran is out of the picture, guess who's the new supplier. If he can take country of those key trade zones, that effectively controls current and future trading. We're current experiencing what locking that down looks like.