The confirming bank confirms the irrevocable letter of credit on the basis of the mandate or request issued by the banks. If the announcing bank guarantees payment of the letter of credit, it is referred to as confirming bank. The primary role of the bank to endorse the letter of credit is complemented by the assumption of the obligation to pay, accept or negotiate the letter of credit. Such an undertaking supplements, not replaces, the issuing bank's already issued guarantee.