It is known from God's commanding David to murder Saul's family over a breach of the Gibeonites' treaty with Joshua that treaties with Enemy goyim are binding, even though Joshua's, Saul's, and David's countries were not exactly the same countries. (2 Shmuel 21)
In the following scenario:
Sate of Israel makes some deal with the Palestinians, be it autonomy, statehood, or property and water rights.
1,000,000 Ephraimites come back from the dead and start marching on Nablus.
I see three potential answers:
Is the State's treaty binding on Moshiach's government?
Is the State's treaty binding only on those in its faction (roughly equivalent to the people who celebrate yom haatzmaut) and not haredim who intentionally distance themselves from the state and not the Ephraimites?
Is the State's treaty binding only on non-resurrected people?