If one invades and occupies another country, one takes the peace movement at home hostage.

Because usually, when one invades a country, one destroys all types of governing infrastructure. One artificially creates a power vacuum and then fills it with one's own forces. One therefore becomes the new ruling body.

Now, of course if one then just leaves this country, one will risk leaving it in a state of lawlessness. Therefore one can then always accuse the peace movement, those who were against the invasion from the start and are now calling for withdrawal, of being irresponsible and working towards anarchy and more destruction in that occupied
country.

I think the best way for the current government to display that it is interested in peace, is to start by throwing those in jail who ordered the initial invasion. Because that was the original crime, after which everything else became a choice between bad decisions.