Atlantic Man?

This point has been raised before, but I can’t find the original question, so I’ll start again. George Smiley is summoned by Oliver Lacon of the Cabinet Office to look into the shooting of General Vladimir on Hampstead Heath. The assassination, for that was what it was, was done with a Russian weapon and a soft-nosed bullet at point blank range that destroyed half the victim’s face. After George has attended the scene, assisted by a Police interpretation of the evidence, he makes his way to the safe house where Lacon, Strickland and Mostyn are gathered. After refreshing himself, but still shaken by events, Smiley joins the others in the sitting room. Strickland is on the telephone to his boss, as to how the wording of the press statement should go.

Lacon: “George, old friend, I’ve hardly said hello……..”
Smiley; “Hello Oliver, and after a pause, “It is still Enderby in charge, is it?”
Lacon: “Yes, it’s still Sir Saul Enderby - he’s been doing marvels, not quite your style. He’s an Atlantic man.

The original questioner wanted to know what was meant by the expression "Atlantic man?" It occurred to me the other day when driving home, that the expression referred to the North Atlantic Treaty Organisation (NATO) of which Britain was a member. The other significant member was the United States, of course, and hence the American association was all-important.
This, so far as I can remember, was the conclusion reached before. But perhaps I have explained the matter more long-windedly? If in any doubt, it pays to refer to the original text, and not rely entirely on the theatrical interpretation for television.