The wordWhen you say missile system do you mean offensive or defensive, I believe you mean defensive, and i am sure you are talking about anti aircraft Surface to air missiles(SAM). SAM’s are either man portable or mounted (vehicle mounted, ship mounted or stand alone)
Now for Nigeria man portable surface to air missiles we have the
which was developed by the British in the 60’s, it saw a lot of action during theduring the early 80’s where it failed badly, The official report stated that, of the 95 missiles fired by the British, only 9 managed to destroy their targets and all of these were slow flying planes and helicopters. Most nations have upgraded their systems to more modern missiles and the .
Then for fixed SAM weapons there is the,
this missile is large and us usually mounted on a vehicle like the AMX-30 chassis. this mobile SAM missile system was credited for one Harrier kill during the Falklands war and It is believed that an Iraqi Roland missile succeeded in shooting down an American A-10 Thunderbolt II at the beginning of the Iraq War, during the battle of Baghdad.
So one answer is Yes Nigeria has a SAM missile system, but is it effective? the battle readiness of this systems haven’t been tested yet in real conflict, but it should be effective against some smaller less advanced and less experienced countries like Ghana, or Kenya. But against countries like Russia, The United States etc NAAAA!!!!!. they would have intelligence already, and they have stealth bombers like the B2 spirit,
Stealth strike fighters like the F-35
and the primary targets of these countries would be the SAM sites. it always is. So effectiveness depends on the country we are in battle with.