Eh maybe. It strains plausibility. We can't even accurately predict where deorbiting satellites will end up... It's pretty hard to imagine a nudge with the required delta-V and accuracy to hit a specific nation. Too far away and you get too much uncertainty, too close and you don't have enough dV for the push. Even if it could be done with today's technology, the potential for error is high, and if you screw up, you've accidentally started another war or "bombed" your own country. Can't imagine that a military with the requisite technology to pull this off wouldn't be able to think of a less-risky way to obliterate their enemy.