In the sense of bringing pressure to bear. My feeling is that it’s more often seen in the negative, well, he hasn’t parked his tanks on the lawn yet. Any idea how far back the phrase goes? One thinks of the much-televised images of North Vietnamese tanks rolling up to the Presidental Palace in Saigon or Chilean tanks outside Salvador Allende’s palace. I wondered if perhaps those images had given birth to the phrase, or did it predate that decade?
It’s a slippery customer to search for on Google Books, I turned up one hit from 1984 for the exact phrase ‘tanks parked on the lawn’ (I’m sure it goes back further) but of course there are many variants on the wording and entering tanks and lawn in the All the words box just floods me with irrelevant hits. I must work on my googlefu on the ABS!
BTW I couldn’t find anything useful in OED, but again, I may have missed something.