No, folks, it was not the much ballyhooed issue of Russian election interference in 2016, which got so much attention because of Trump's bungled and false statements at the press conference. Oh yes, for those of us who are convinced he is a bought out stooge of Putin, this all was very delicious, but it was far from the most important issue dealt with in Helsinki.
As always, the most important issue between Russia and the US is nuclear weapons, not Ukraine or NATO expansion eastward or even Putin murdering innocent opponents. Of course we have this awful problem that we in the US do not know what was discussed for 2 hours privately between Trump and Putin in Helsinki. We are getting claims out of Moscow about supposed deals made, mostly about Syria in terms of specifics, but there remains zero knowledge among US authorities supposedly responsible for these matters of what the deals are or their details. As it is, most of the Syrian stuff looks like basically status quo arrangements made on the ground between US and Russian military, most of this dating back to the Obama era. We needed a summit for this?
Anyway, getting back to the most important issue, nuclear weapons, what we have been provided with is a vague and confused statement: that the INF and "new" START treaties "will be extended." Well, that sounds nice, but it has some problems, especially with the INF part, although given that START was an Obama treaty with Medvedev, this is some solace given Trump's propensity to simply end anything that Obama did, just because.
The Intermediate Nuclear Force (INF) was agreed to in Dec. 1987 by US President Ronald Reagan and Soviet President Gorbachev. It is a permanent treaty requiring no special extension. It bans missiles of intermediate range of especial danger to NATO nations in western Europe. Until 2014 it was followed by both sides. Then in 2014 Putin adopted the RS-26 missile that violates the treaty, although he has denied it does. But US SecDef Mattis thinks it does.
So, what Trump should have had as his top priority in Helsinki and before while visiting NATO allies, whom he dissed, including the EU as our "worst foe," would have been to demand that Putin get rid of the RS-26 missile that violates the INF treaty. Instead we are told that he and Putin have agreed to "extend" it and the START. This is plain awful, but not surprising.