In response to the UK's "guarantee" of Poland of 31 March 1939, Hitler, enraged by the UK's move proclaimed "I shall brew them a devil's drink". In a speech in Wilhelmshaven for the launch of the battleship Tirpitz, Hitler threatened to denounce the agreement if the UK persisted with its "encirclement" policy, as represented by the "guarantee" of Polish independence. On 28 April 1939, Hitler denounced the AGNA. To provide an excuse for its denunciation of and to prevent the emergence of a new naval treaty, the Germans began refusing to share information about their shipbuilding, leaving the UK with the choice of either accepting the unilateral German move or rejecting it, thus providing the Germans with the excuse to denounce the treaty.