When a citizen of the United States dies in a foreign country and leaves, by any lawful testamentary disposition, special directions for the custody and management, by the consular officer, or in his absence a diplomatic officer, within whose jurisdiction the death occurred, of the personal property in the foreign country which he possessed at the time of death, such officer shall, so far as the laws of the foreign country permit, strictly observe such directions if not contrary to the laws of the United States. If such citizen has named, by any lawful testamentary disposition, any other person than a consular officer or diplomatic officer to take charge of and manage such property, it shall be the duty of the officer, whenever required by the person so named, to give his official aid in whatever way may be practicable to facilitate the proceedings of such person in the lawful execution of his trust, and, so far as the laws of the country or treaty provisions permit, to protect the property of the deceased from any interference by the authorities of the country where such citizen died. To this end it shall be the duty of the consular officer, or if no consular officer is present a diplomatic officer, to safeguard the decedent's property by placing thereon his official seal and to break and remove such seal only upon the request of the person designated by the deceased to take charge of and manage his property.