The Islamic State became as big and powerful as it is now because Obama pulled out of Iraq. With thousands of US boots on the ground Iraq the IS never got a foothold. It only did because the Obama cut and ran.
Obama originally was going to pull almost completely out of Afghanistan too, but redfacedly changed plans after he saw how badly the Iraq pullout backfired.
Obama also failed to follow through on his so-called “red lines” in Syria regarding Assad, before the IS became large, thus feeding the Islamic State which saw Obama was puppeteer pulling strings but not following through on his promises.