Agreed in 2006 of 2% target, then had to reiterate the target in 2014 since many members did not meet 2% target. "Members that fell short at the time promised to meet their obligations by 2024" .. it is an obligation not some "aspirational goal" as some have mentioned below.
The agreement does not even call for European nations to spend 2% on NATO, it calls for them to simply spend 2% of their GDP on building up their armed forces. When Trump claims that the failure to meet this future goal means that they owe the US billions of dollars simply illuminates how little he understands about NATO in general.
Yeah, that Trumpian factoid has long been debunked. Formally true, but 2% is also an aspirational goal, to be met a decade from now. That parallels, at worst, Trump making it harder to meet the Paris pact's requirements a decade from now.
Those agree with him. The 2% is an aspirational goal. Here is an actual quote from the Economist article you linked to:
"At a summit in 2014, NATO reiterated its commitment to the 2% target. Members that fell short at the time promised to meet their obligations by 2024."
Here is the actual text of the relevant portion of the statement:
"Allies currently meeting the NATO guideline to spend a minimum of 2% of their Gross Domestic Product (GDP) on defence will aim to continue to do so. Likewise, Allies spending more than 20% of their defence budgets on major equipment, including related Research & Development, will continue to do so.
Allies whose current proportion of GDP spent on defence is below this level will:
halt any decline in defence expenditure;
aim to increase defence expenditure in real terms as GDP grows;
aim to move towards the 2% guideline within a decade with a view to meeting their NATO Capability Targets and filling NATO's capability shortfalls."
Whoever told you that NATO countries were failing to meet their commitments was lying to you so that you would support them politically. Consider not trusting them.
"At a summit in 2014, NATO reiterated its commitment to the 2% target. Members that fell short at the time promised to meet their obligations by 2024."
But, again, even in the worst light possible, a country not spending enough on military spending to meet some stated target doesn't compare to tossing out treaties based on a whim.
From the perspective of the US Constitution, the Paris Accords are most certainly not a treaty. Treaties require a 2/3 vote of approval in the Senate.
The tradition of significant international agreements made deliberately short of "treaties" goes back to FDR/Churchill and the Atlantic Charter, if not further.
The proof is in the pudding, here. This is a giant bat signal that the USA is unable to uphold its international obligations. Preen about the Constitution all you want, but that doesn't change the fact that people are going to take the USA's public commitments with a giant grain of salt now, and this will shift smaller countries' orientation to relatively trustworthy large countries, many of which are actively hostile to American interests.
The main confusion seems to stem from the fact that the 2% goal (agreed upon in 2014, to be met by 2024) is not "money for NATO", but how much eah member state shall spend on their own armies.
"Allies whose current proportion of GDP spent on defence is below [two percent] will... aim to move towards the 2% guideline within a decade...." [emphasis mine]
Congrats to the US, but this is not a fair comparison. This is not a US vs Germany/France thing, this is a US vs the entire world thing. Maybe if the USA would pull out of NATO, that would be fair, but even so... the 2% is a guideline.
The US has released a huge percentage of the total CO2 released into the atmosphere in the past 150 years. Donald Trump is not a believer in climate change, and that is why he wanted out, which is frankly insane from the president of the most powerful country in the world.
It's a guideline and spending money does not magically solve problems. The fact that the USA as a complex, bloated, bureaucratic military industrial complex does not mean that it's the right way to build a military.
All the money the USA spends on its military and after 17 years they've failed to suppress and army comprised of hastily-trained insurgents armed with 70 year old rifles and rudimentary explosives. And this is hardly the first quagmire of this sort the USA has been involved in.
The harsh reality is the US govt doesn't want a strong NATO. If France and Germany decided tomorrow to spend similarly to the US on defense there would be a collective gum swallowing moment in DC on both wings. It would mean that the EU isn't so toothless and that inevitably in some future that the US would have to go toe to toe with them in a military conflict. Regardless of outcome of such a conflict, it would mean more spending in the US to ensure against not only China and Russia (nominally) in a fashion far more unsustainable than it is today. The last time Europe was a legitimate region in terms of military power was the last world war. And we know that wasn't a pretty sight for all.