Biggest error was New START and I think the GOP should have invested far more political capital into that one. And, it should have been invested 6 months ago.
It has really made us VERY vulnerable to attacks by non Russian Nuclear proliferators
The end result is
1) A much more vulnerable USA
2) Russia and every other country, including proliferators such as North Korea and Iran, are much stronger
3) A much less stable world due to artificial limits on the US
All is not lost. Tactical nukes were not part of this agreement. To a certain extent, Strategic nukes and their delivery systems are obsolete.
Perhaps we may have responsible leadership when it comes to managing or Tactical capability