however, the ink had barely dried on fcc approval of the trade when the united states department of justice opened an investigation into the deal, on claims that nbc had employed extortion and coercion. the justice department believed that nbc abused its power as a broadcast network by threatening to withhold or cancel affiliations with westinghouse-owned stations unless the latter company agreed to the network's terms and participate in the trade. specifically, it was determined that nbc threatened to drop its programming from both wptz and boston's wbz-tv; to withhold a primary affiliation from newly acquired kdka-tv in pittsburgh (that station would sign with cbs as a primary affiliate); and to withhold or pull an nbc affiliation from any other major-market station westinghouse would purchase in the future. based on these findings, a civil antitrust suit was filed against nbc and its parent company rca, on behalf of westinghouse in december 1956. during this ordeal nbc attempted to circumvent the investigation by trading the philadelphia stations in return for rko general's radio and television properties in boston, which would have resulted in wbz-tv losing its nbc affiliation to rival station wnac-tv; the proposed nbc-rko station swap never materialized.