John Thune actually said...

Russia will threaten to withdraw from the treaty should the United States expand its current missile defense capabilities.

is there a chance the administration could decide against a new bomber, ALCM, or follow-on ICBM?

The administration will invest $100 billion over the next decade in nuclear delivery systems.

the decision to agree to a limit of 700 deployed strategic delivery vehicles did not result from a change in the security environment