Arteta already has the bonus of William Saliba beginning his Arsenal career after a loan spell with St. Etienne.
But Campbell says the 19-year-old isn't enough to solve the Gunners' notorious defensive woes.
He told the Chronicles of a Gooner podcast: "We made a very astute signing last year which many gave the club stick for: Saliba.
"At least we've got a centre-half, a big, strong, quick, centre-half who is going to go straight into that side. He has to.
"Do we need another one? Yes we probably do. Will we get one? Who knows?
"If we can get Saliba in and bed him in nicely then at least the defence is a lot younger and is a lot stronger."
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