IN THE continuing struggle between Christians and Syrians in Lebanon, a critical element has been lost sight of. Much can be said about the methods and motives of the Christians, but one thing is clear: They are Lebanese. The country in which they are striving for a place is theirs. Their right to be there and to contest cannot be denied.

The same cannot be said of the Syrians. They are, after all, foreigners. They were invited in by the Lebanese government to police the internal conflict that was ranging in the mid-1970s, but their role has since become closer to that of an occupying force. In any event, they have no legitimate claim to any role in Lebanon apart from that accorded to them by the Lebanese government.

This seems to us the essence of what is still going on around the Christian city of Zahle in the Bekaa valley east of Beirut. The Syrians are refusing to acknowledge that their forces are meant to be only temporary guests. It is not that they have been firing on Lebanese Christian areas, killing some hundreds of citizens in the process. Nor is it just they are insisting that any Lebanese army units in the area come under their command and control, not the other way around. They are making suggestive noises to the effect that their security requirements compel them to divorce their presence from any considerations of Lebanese sovereignty and to stay there for an indefinite basis on their own. They are using their influence in Lebanon's Moselem community, and the widespread fear that civil war will resume full blast if their "peace-keeping" forces depart, to ensure that their five-year-old invitation to Lebanon is not withdrawn.

As we indicated the other day, we are not sanguine about the possibilities of putting an end to Lebanon's multi-layered misery while the Arab-Israeli dispute remains unresolved. In any approach even to mitigating Labanon's tragedy, however, one principle must be underlined: Lebanon for the Lebanses. The country is plainly incapable of mustering either the strength on its own or the international protection to keep its sovereignty inviolate. First the Palestinians swept in, uninvited, and different kinds of Israeli and Syrian intervention followed. It is different now to separate out any one of these interventions and resolve it apart from the others. The main point remains that eventually the Lebanese, and the Lebanese alone, must be allowed to decide which foreigners remain on their soil.