The NATO spending discussion maybe should be in the foreign policy thread, but since it is here and you asked, as a quick response:
"...
Official NATO data show that non-US members’ defense spending increased in each of the two years prior to Trump’s presidency – by 1.6% in 2015 and 3.0% in 2016. The increases came after NATO members recommitted to the 2%-of-GDP guideline at the 2014 summit in the wake of Russia’s annexation of Ukraine’s Crimea region.
Non-US members’ defense spending increases in each year of the Trump era were bigger than their increases in 2015 and 2016 – the increases were 5.9% in 2017, 4.3% in 2018, 3.6% in 2019 and 4.6% in 2020 – and NATO Secretary General Jens Stoltenberg
gave Trump at least partial credit. But Trump is wrong when he claims he reversed a downward trend. ..."
Obama had also made this part of the discussion and Trump expanded and amplified it, albeit based on a misrepresentation or misunderstanding of the 2% goal and how it actually works. But making it part of the discussion seems to have kept up the preexisting pressure and moved the needle in the right direction, if you agree with the pretty consistent general US position about NATO partner spending on their own defense budgets.