Border tensions rise as Hungary releases people smugglers and Austria tightens security.

Austria has summoned the Hungarian ambassador after Hungary's decision to release foreigners convicted of human trafficking, citing overcrowded prisons. Austria regards the release of human traffickers as a security threat as it is a prime destination for smuggled migrants heading for the heart of the EU via Hungary from the Balkans. Hungarian Prime Minister Viktor Orban's nationalist anti-immigration policies have put him in conflict with the EU and drawn criticism from the UN refugee agency.