True to form, the Kremlin has interpreted Trump’s conciliation as a sign of weakness. Notably, they have already discounted Trump’s blustery, threatening exterior as a put-on.
Additional sanctions would have no effect on Russian thinking.
President Trump should note that negotiations in the framework of diplomacy are fundamentally different from negotiations in business. In business, in case of breach, one has recourse to the courts. In diplomacy, there is no such recourse. This is why Henry Kissinger said that diplomacy must be backed by force, or it becomes an empty exercise.