According to BBC political editor, Laura Kuenssberg, Johnson is convinced that Putin seems "bent on a full scale invasion" and should announce the "first barrage of economic sanctions" later.
The key word there being first in my view. That suggests that the sanctions are likely to not be too comprehensive. The line of thinking here together with what is likely to be proposed by the EU is that 'Russia did not technically invade Ukraine, so we don't technically have to be so harsh in imposing sanctions'.
Political theater at its best, folks.