VATICAN CITY (Reuters) - Pope Francis urged political leaders on Monday to defend migrants, saying their safety should take precedence over national security concerns and that they should not be subjected to collective deportations. His challenge to politicians, made in a comprehensive position paper on migrants and refugees, again appeared to put him at odds with the restrictive policies of a number of governments dealing with growing popular anti-immigrant sentiment. "Solidarity must be concretely expressed at every stage of the migratory experience – from departure through journey to arrival and return," he said in a message ahead of the Roman...