Situations of crisis or force majeure are also liable to put at risk the essential functions of a Member State. In order to strengthen mutual trust between the Member States and to improve coordination at Union level, implementing powers should be conferred upon the Council to adopt an implementing decision authorising a Member State to apply the derogations and the solidarity measures provided for in this Regulation where the conditions laid down are met. The time period for the application of the measures authorised by the initial implementing decision should be three months. It should be possible to extend that period for a further three months upon confirmation by the Commission that the situation of crisis or force majeure persists. The Council should be empowered to further extend the authorisation to apply the derogations and the solidarity measures, by up to three months, on the basis of a Commission proposal, if the circumstances justifying the extension of the derogations and solidarity measures persist. It should be possible to extend that period by a further three months upon confirmation by the Commission that the situation persists. The Council should be empowered to repeal the application of the measures on the basis of a Commission proposal when the circumstances justifying the application of the derogations and solidarity measures have come to an end. It should be possible for the decision extending the authorisation to amend the derogations applied. In exercising their powers and carrying out their responsibilities, the Commission and the Council should ensure at all times that the principles of proportionality and necessity are respected.