I’m sure he is pulling them back as we speak.
Check it out:

President Obama called on Russian President Vladimir Putin to pull back his troops from Ukraine’s border on Friday during a phone call between the two leaders.

Obama noted that the Ukrainian government has pursued “a restrained and de-escalatory approach” in the crisis, the White House said.

He urged Russia to support Ukraine’s democratic process and to “avoid further provocations, including the buildup of forces on its border with Ukraine.”