Pres Trump is very unpopular amongst the leftist and liberal populations in Europe, and he was widely criticized in the media for disrupting the NATO Summit meeting that he attended in Brussels. Despite this, Trump did a very good deal for NATO, because he disrupted their cozy little get-together to mope about Russia in Crimea and Eastern Ukraine and he actually accomplished something important.
He insisted, after last year putting all NATO European members on notice, that the US will no longer foot the bill for ca. 90% of NATO costs, but will insist that they each contribute at least 2% of their GDP as required by the actual NATO treaty. He claimed at his press conference after the NATO summit that European contributions to NATO will now increase from b$12 to b$33 and will be rising. Although this will not reduce US expenditures for NATO, it will reduce the %age of US support for NATO and make it more European as it is supposed to be.
Against the backdrop of EU disarray over Brexit and widespread demonstrations against his visit to the UK, Trump will go to his meeting with Pres Putin of Russia in Finland, with something concrete in his brief case, namely a large expansion of NATO. Putin is known to regard NATO with great alarm, seeing all expansion of NATO as a threat and encirclement of Russia. Now to get some relief from Trump and NATO, Putin will have to make a deal, something Trump is always looking for.
Here is a possible deal, Putin withdraws from Eastern Ukraine (Donbask) and gives up all claims on any other Ukrainian territory, in exchange for US recognition of Russian sovereignty in Crimea. This would resolve two major conflicts that have been bedevilling Europe and Russian-US relations for some years. There is no doubt that Putin invaded both these regions because he gambled that Pres. Obama would never use force to prevent him. While with Trump the opposite is true. But, the annexation of Crimea is now a fait accompli, and no-one, not even Trump, can reverse it.
Also, in exchange for the recognition of Russian sovereignty over Crimea, Putin will have to agree to ensure the expulsion of all Iranian forces from Syria. This will be in US interests since it will reduce the power of Iran and will reduce the likelihood of a dangerous conflict between Israel and Iran, which could have severe global repercussions. But, Putin will only do this if Trump tacitly recognizes Russian influence in Syria and the Eastern Mediterranean. This will be possible if there are good relations between the two counties. One thing Russia can’t afford to do is to get into another arms race with the US and NATO.