The president of Estonia took to Twitter on Thursday to defend its role in NATO after Donald Trump said he may not come to allies' aid as president if they didn't pay enough for their own defense.

President Toomas Hendrick Ilves said that Estonia is one of only five NATO allies that meets the goal set two years ago to spend at least 2 percent of its gross domestic product on defense. He also pointed out that Estonia fought "with no caveats" in Afghanistan when the U.S. invoked Article 5, which requires NATO allies to respond to an attack on one country as if they themselves had been attacked.

Estonia is 1 of 5 NATO allies in Europe to meet its 2% def expenditures commitment. Fought, with no caveats, in NATO's sole Art 5 op. in Afg — toomas hendrik ilves (@IlvesToomas) July 21, 2016

We are equally committed to a l l our NATO allies, regardless of who they may be. That's what makes them allies. — toomas hendrik ilves (@IlvesToomas) July 21, 2016

No reason to read so much into my sentences about Estonia's role in NATO. I'm simply Sgt Joe Friday: "Just the facts, ma'am, just the facts" — toomas hendrik ilves (@IlvesToomas) July 21, 2016



Asked if he would come to the aid of Baltic countries if they are invaded by Russia and invoke Article 5, Donald Trump told the New York Times Wednesday that many NATO members "aren't paying their bills," and that that would come into consideration if one fell under attack.

"Have they fulfilled their obligations to us? If they fulfill their obligations to us, the answer is yes," Trump said.

And if not, the Times pressed him?

"Well, I'm not saying if not. I'm saying, right now there are many countries that have not fulfilled their obligations to us," Trump continued.

The only time Article 5 has ever been invoked was by America after 9/11. Questioned about Trump's criticism of NATO, Secretary General Jens Stoltenberg said at a defense ministerial in Brussels last month that many European troops died while fighting on behalf of America as a result of that, proving how valuable the alliance can be to everyone in it, including the U.S.

At the ministerial, as well as at this month's Warsaw Summit, NATO members focused heavily on beefing up the alliance's defenses along its eastern flank to protect against Russian aggression. This includes the deployment of four multinational battalions to Estonia, Latvia, Lithuania and Poland.