Emergency conditions may lead to relaxation of the traditional American rule, based upon the assumption that public employment is a privilege and upon security grounds, that aliens are ineligible for governmental positions--especially positions in the military establishments. In 1946 Congress suspended statutory provisions prohibiting the employment of aliens.[133] Thus the Secretary of the Navy could authorize the Navy Department to employ non-citizens whose special technical or scientific knowledge or experience would be of benefit to the military services of the United States. The wisdom of this legislation may be more readily appreciated when it is remembered that German rocket experts like Dr. Werner von Braun were able to serve in the United States rather than behind the Iron Curtain. Similarly, as illustrated by the Selective Service Act of 1948,[134] effective mobilization of the labor force requires exemption of some specially skilled persons from military conscription. This Act authorized the President to provide for the deferment from training and service certain categories of individuals in many different fields as found to be necessary to the maintenance of the national health, safety, or interest. Work stoppages are the nemesis of any defense production program. The wartime efforts to prevent or speedily terminate such stoppages are reported in the next section, on the theory that they were primarily coercive in nature. The Defense Production Act of 1950,[135] however, clearly reflects the statutory trend in the United States against the outlawing of strikes in time of emergency. Section 502 of the Act emphasizes that national policy is to place primary reliance upon the parties to any labor dispute to settle their differences through negotiation and collective bargaining, making full use of available mediation and conciliation facilities. All settlements should be made in the national interest. The President is to initiate strike settlement conferences, with representatives of the public present, but no action inconsistent with the Labor-Management Relations Act of 1947 may be taken.[136] Current information on the availability of essential skills must be maintained. The National Science Foundation Act of 1950 included among the functions of the agency that of maintaining a register of scientific and technical personnel and providing a central clearinghouse for information covering all scientific and technical personnel in the United States.[137]