The answer to the question is found in this new Vatican document:
The covenant that God has offered Israel is irrevocable. “God is not man, that he should lie” (Num 23:19; cf. 2 Tim 2:13). The permanent elective fidelity of God expressed in earlier covenants is never repudiated (cf. Rom 9:4; 11:1-2). The New Covenant does not revoke the earlier covenants, but it brings them to fulfilment.
For Christians, the New Covenant in Christ is the culminating point of the promises of salvation of the Old Covenant, and is to that extent never independent of it. The New Covenant is grounded in and based on the Old, because it is ultimately the God of Israel who concludes the Old Covenant with his people Israel and enables the New Covenant in Jesus Christ. Jesus lives during the period of the Old Covenant, but in his work of salvation in the New Covenant confirms and perfects the dimensions of the Old. The term covenant, therefore, means a relationship with God that takes effect in different ways for Jews and Christians. The New Covenant can never replace the Old but presupposes it and gives it a new dimension of meaning, by reinforcing the personal nature of God as revealed in the Old Covenant and establishing it as openness for all who respond faithfully from all the nations (cf. Zech 8:20-23; Psalm 87).
That raises the further question of how the Old and the New Covenant stand in relation to one another. For the Christian faith it is axiomatic that there can only be one single covenant history of God with humanity.
The New Covenant for Christians is therefore neither the annulment nor the replacement, but the fulfilment of the promises of the Old Covenant.
the covenant that God concluded with Israel has never been revoked but remains valid on the basis of God’s unfailing faithfulness to his people, and consequently the New Covenant which Christians believe in can only be understood as the affirmation and fulfilment of the Old. Christians are therefore also convinced that through the New Covenant the Abrahamic covenant has obtained that universality for all peoples which was originally intended in the call of Abram (cf. Gen 12:1-3).