We assess the conjunctural impact of price insulating policies on spatial price transmission of maize, rice and wheat in Cameroon, Kenya and Tanzania in the period 2005-2015. We therefore separately estimate the impact of trade policies within two regimes of behaviour of the domestic price series: the first regime with an increasing trend of domestic prices and the second regime with a decreasing trend. We find a significant impact of trade policies in both price regimes. This is however much larger if prices are increasing. Our results show that trade policies were able to insulate the three analyzed countries from the price shocks on international markets during the food price spike crisis 2007/2008. Although the impact of these policy instruments proved to be relevant as a counter-cyclical measure during the food price spike crisis, these policies cannot be regarded as structural long-term solutions. This paper extends the existing literature on spatial price transmission in agricultural markets by estimating the impact of tariff and non-tariff trade policies using monthly data. Employing monthly data allows for a more precise assessment of short-lived movements in the analysed series, which could disappear due to a time aggregation bias at lower yearly frequencies. While monthly price series are provided in the GIEWS database, we obtain monthly ad-valorem equivalent tariff rates by a time disaggregation of the yearly effectively applied weighted average tariff rate from the WITS/UNCTAD- TRAINS database through the monthly trade policies from the FAO-FADPA. By presenting high frequency analyses and techniques that are able to detect non-linearities in the Data Generating Process (DGP), this study provides results which differ from what is stated in the standard literature (Anderson and Nelgen, 2012a) (Anderson and Nelgen, 2012b) (Anderson and Nelgen, 2012c).