Suicide bomb outside US embassy in Ankara Emergency services at the scene of the US embassy incident (APTN) The main domestic security threat comes from the separatist Kurdistan Workers Party (PKK), deemed a terrorist group by the United States, European Union and Turkey, but the PKK has focused its campaign largely on domestic targets. Turkey has led calls for international intervention in neighbouring Syria and is hosting hundreds of NATO soldiers from the United States, Germany and the Netherlands who are operating a Patriot missile defence system along its border with Syria, hundreds of kilometres away from the capital. The US Patriots were expected to go active in the coming days.