By Gabriela Baczynska and Alissa de Carbonnel BRUSSELS/STRASBOURG (Reuters) - The European Union will nearly treble its spending on frontier defence provided by a new European Border and Coast Guard under proposals unveiled on Tuesday to tackle a migration crisis that threatens Europe's security and passport-free travel area. With Greece and Italy struggling to control hundreds of thousands of people, including Syrian refugees, the bloc's executive the European Commission proposes taking the power to deploy EU forces without the consent of the member state concerned -- an idea that has already hit resistance in national capitals and which many see as impractical. The Commission proposal says the EU agency overseeing the frontiers should be able to "intervene immediately in crisis situations" and deploy border guards from the standby pool drawn from other national border guard forces.