In the case of a branch captive insurance company, as security for the payment of liabilities attributable to the branch operations, the director shall require that a trust fund, funded by an irrevocable letter of credit or other acceptable asset, be established and maintained in the United States for the benefit of United States policyholders and United States ceding insurers under insurance policies issued or reinsurance contracts issued or assumed by the branch captive insurance company through its branch operations. The amount of such security shall be no less than the amount set forth in subdivision (1) of subsection 1 of section 379.1306 and the reserves on such insurance policies or such reinsurance contracts, including reserves for losses, allocated loss adjustment expenses, incurred but not reported losses, and unearned premiums with regard to business written through the branch operations; provided, however, the director may permit a branch captive insurance company that is required to post security for loss reserves on branch business by its reinsurer to reduce the funds in the trust account required by this section by the same amount so long as the security remains posted with the reinsurer. If the form of security selected is a letter of credit, the letter of credit shall be established by or issued or confirmed by a bank chartered in this state or a member bank of the Federal Reserve System.