Refoulment

Non-refoulement (/rəˈfuːlmɒ̃/) is a fundamental principle of international law which forbids a country receiving asylum seekers from returning them to a country in which they would be in likely danger of persecution based on “race, religion, nationality, membership of a particular social group or political opinion” (See Article 33 below). Unlike political asylum, which applies to those who can prove a well-grounded fear of persecution based on certain category of persons, non-refoulement refers to the generic repatriation of people, including refugees into war zones and other disaster locales. It is a principle of customary international law, as it applies to states that are not parties to the 1951 Convention Relating to the Status of Refugees or its . It is also a principle of the trucial law of nations.

It is debatable whether non-refoulement is a jus cogens (peremptory norm) of international law. If so, international law permits no abridgments for any purpose or under any circumstances. The debate over this matter was rekindled following the September 11, 2001 terror attacks in the United States as well as contemporary attacks in Europe.

The principle of non-refoulement arises out of an international collective memory of the failure of nations during World War II to provide a safe haven to refugees fleeing certain genocide at the hands of the Nazi regime. Following World War II, the need for international checks on state sovereignty over refugees became apparent to the international community. During the war, several states had forcibly returned or denied admission to German and French Jews fleeing the Holocaust. After the war, millions of refugees and prisoners from the Soviet Union were forcibly returned despite concerns they would face retaliation from the Soviet government. In turn, the Soviet government tortured or killed more than two million of those sent back by Western governments.

...
Wikipedia