Why Britain retains its veto over arms for Argentina

Why does Britain resist US pressure to release arms containing British components for sale to Argentina?

Because Britain still plans against a renewed Falklands threat, and lifting the veto would be strategically and politically costly.

Britain still treats Argentine military capability as relevant to Falklands security. It therefore sees no strategic reason to approve systems containing British components when those systems could narrow the islands' defensive margin. The United States cannot treat the veto as cost-free unless it is also willing to assume the burden of guaranteeing the Falklands. Relaxing the controls would additionally impose an immediate domestic political cost on any British government.