The root of most of today's awfulness lies, I believe, in oil and banking. Ultimately these are symptoms of the larger problems of greed and sociopathy, but those aren't as actionable.
I don't think there's much debate that the Middle East is a dysfunctional as it is because of oil. If the world moved to renewable resources, as Germany is doing, there'd be an opportunity to begin repairing the Middle East.
Let's look at Ukraine. Why is there a war? First off, the austerity con:
1. Banker-governments lend money to corrupt government
2. Corrupt government puts much of it in their personal bank accounts
3. Borrowing country's debt load eventually builds to risky levels.
4. Because of the increased risk, interest on loans to corrupt government shoots up, so now the country can't pay its debts... Unless...
5. Borrowing country agrees to austerity and all sorts of other awful stuff in exchange for the privilege of paying back all of its loans to the banker-governments at non-usurious interest rates.
6. The corrupt government flees with billions, invests it with bankers.
7. The austeritized nation sells their services and possessions to banker-governments really cheaply because they desperately need the cash.
8. The bankers effectively resell what they've purchased cheaply, at a huge profit.
In the case of Ukraine, the US and Russian oligarchs, each fronted by their respective governments, fought over who was going to take over at step 5. Each side ended up grabbing part of the country although that's not totally clear yet, so we have a war. So bankers can make more money.
There's also an "oil" issue with Ukraine, namely the natural gas pipeline from Russia to Europe which makes things all the more perilous.
So what can a president do? A president can lead the charge to renewable energy resources, and get the bankers under control. Until that's done, disaster and misery will continue to abound.