Madrid, May 28 The US Ambassador to Spain, Benjamin Leon, has urged Spain to be "very careful" about China's involvement in sensitive sectors like telecommunications, data management and defence. In his first public appearances since assuming office in February, Benjamin Leon warned that China's growing presence in strategic sectors could pose risks to security, technology and critical infrastructure. He voiced concerns about giving public contracts to companies working with Chinese technology firm Huawei that the US regards a security risk, Greek media outlet Tovima reported on Wednesday."I don’t think that attains the level of security at which Spain and the…