The novelty of this paper is to use national rate of assistance (NRA) to assess the impact of domestic support on food security vulnerability to trade. We first build a theoretical framework linking the vulnerability of food security to trade and national policy intervention in agriculture. Second, we measure the impact of national policy responses to 2008 price surge using the NRA on importable food products for 42 countries over the period 1995-2010. Our results suggest that most developing countries have used their possibility to play with the NRA level to compensate the effects of the 2008 food price surge.