Here’s my superficial reading of the “Countering America’s Adversaries Through Sanctions Act.” Apart from relatively minor tightenings of the screws (which might nonetheless hurt a good deal), there are three major innovations, as far as I can see:
(a) The bill removes the president’s discretion, making some of the sanctions mandatory (with only a national security exemption), and requires congressional approval to weaken or lift any sanctions, current or future.
(b) The bill gives the president discretionary powers to ban US-based and US-linked companies from taking any part in building new export pipelines from Russia, such as North Stream 2.
(c) The bill opens a procedural path to restricting or blocking US investment in Russian sovereign, sub-sovereign and quasi-sovereign debt.
Part (b) would have fit the logic of Obama’s sanctions: “So you want to keep Ukraine unstable? Go ahead, but bear in mind you won’t be able to build new pipelines to bypass the chaos.” It also assumes a simple incentive structure: leave Ukraine alone and the sanctions will be at least weakened. Obama’s sanctions operated like a boa constrictor, sedate and overly cautious, perhaps, but appropriately rational.
In contrast, the promises and logic of the 2017 bill tend to the surreal; perhaps paranoia is a winning stratagem after all. If Kremlin’s rule of thumb is “retaliate by bombing Voronezh,” “keep the sanctions coming” might be the right principle. However, you cannot count on being able to safely drive your adversary to suicide.