An employee serving in a foreign area may be granted a danger pay allowance on the basis of civil insurrection, civil war, terrorism, or wartime conditions which threaten physical harm or imminent danger to the health or well-being of the employee. A danger pay allowance may not exceed 35 percent of the basic pay of the employee, except that if an employee is granted an additional differential under section 5925(b) of this title with respect to an assignment, the sum of that additional differential and any danger pay allowance granted to the employee with respect to that assignment may not exceed 35 percent of the basic pay of the employee. The presence of nonessential personnel or dependents shall not preclude payment of an allowance under this section. In each instance where an allowance under this section is initiated or terminated, the Secretary of State shall inform the Speaker of the House of Representatives and the Committee on Foreign Relations of the Senate of the action taken and the circumstances justifying it.