(a) A claim may be settled only if presented in writing within two years after it accrues, except that if it accrues in time of war or armed conflict, or if war or armed conflict intervenes within two years after it accrues, and if good cause is shown, the claim may be presented not more than two years after the termination of the war or armed conflict.

(b) For the purposes of this section, a war or armed conflict is one in which an armed service of the United States is engaged. The dates of commencement and termination of an armed conflict will be as established by concurrent resolution of Congress or by determination of the President.