Extra I and missing E
IE is the international country code for the Republic of Ireland and is well known for fuckery with taxes in Europe. Companies register a subsidiary in Ireland, and the sales people all across Europe are employed by that company even though they never set foot in Ireland. All sales in all countries are therefore Ireland sales and the company only pays taxes on the sales income in Ireland. Which is the lowest rate in Europe.
In other words, Trump is pointing out that NATO funding is not the only place where there is financial fuckery in Europe.