In May 1939, a ship called the St. Louis departed from Hamburg, Germany, with 937 passengers, most of them Jews fleeing the Holocaust. They had been promised disembarkation rights in Cuba, but when the ship reached Havana, the government refused to let it dock. The passengers made desperate pleas to the U.S., including directly to President Franklin D. Roosevelt, to allow them entry. Roosevelt never responded. The State Department wired back that they should “wait their turn” and enter legally.

As if that were a realistic option available to them.

After lingering off the coast of Florida hoping for a merciful decision from Washington, the St. Louis and its passengers returned to Europe, where the Nazis were on the march. Ultimately, 254 of the ship’s passengers died in the Holocaust.

In response to this shameful failure to provide protection, the nations of the world came together and drafted an international treaty to protect those fleeing persecution. The treaty, the 1951 Refugee Convention, and its 1967 Protocol, has been ratified by more than 75% of nations, including the United States.

Because the tragedy of the St. Louis was fresh in the minds of the treaty drafters, they included an unequivocal prohibition on returning fleeing refugees to countries where their “life or freedom would be threatened.” This is understood to prohibit sending them to a country where they would face these threats, as well as sending them to a country that would then send them on to a third country where they would be at such risk.

All countries that are parties to the Convention and Protocol Relating to the Status of Refugees are bound by this prohibition on return (commonly referred to by its French translation, “nonrefoulement”). In the U.S., Congress enacted the 1980 Refugee Act, expressly adopting the treaty language. The U.S. is also a party to the Convention Against Torture, which prohibits the return of individuals to places where they would be in danger of “being subjected to torture.”

In both Trump administrations, there have been multiple ways in which the president has attempted to eviscerate and undermine the protections guaranteed by treaty obligation and U.S. law. The most drastic among these measures have been the near-total closure of the border to asylum seekers and the suspension of entry of already approved and vetted refugees.

However, none of these measures has appeared so clearly designed to make a mockery of the post-World War II refugee protection framework as the administration’s proposals and attempts to send migrants from the U.S. to Libya and Rwanda.

Although there are situations in which the U.S. could lawfully send a migrant to a third country, it would still be bound by the obligation not to return the person to a place where their “life or freedom would be threatened.” The choices of Libya and Rwanda — rather than, for example, Canada or France — can only be read as an intentional and open flouting of that prohibition.

Libya is notorious for its abuse of migrants, with widespread infliction of torture, sexual violence, forced labor, starvation and slavery. Leading advocacy groups such as Amnesty International call it a “hellscape.” The United Nations High Commissioner for Refugees has stated in no uncertain terms that Libya is not to be considered a safe third country for migrants. The U.S. is clearly aware of conditions there; the State Department issued its highest warning level for Libya, advising against travel to Libya because of crime, terrorism, civil unrest, kidnapping and armed conflict.

Although conditions in Rwanda are not as extreme, the supreme courts of both Israel and the United Kingdom have ruled that agreements to send migrants to Rwanda are unlawful. The two countries had attempted to outsource their refugee obligations by calling Rwanda a “safe third country” to which asylum seekers could be sent to apply for protection.

Israel and the U.K.’s highest courts found that Rwanda — contrary to its stated commitment when entering these agreements — had in fact refused to consider the migrants’ asylum claims, and instead, routinely expelled them, resulting in their return to countries of persecution, in direct violation of the prohibition on refoulement. The U.K. court also cited Rwanda’s poor human rights record, including “extrajudicial killings, deaths in custody, enforced disappearances and torture.”

If the Trump administration had even a minimal commitment to abide by its international and domestic legal obligations, plans to send migrants to Libya or Rwanda would be a nonstarter. But the plans are very much alive, and it is not far-fetched to assume that their intent is to further undermine internationally agreed upon norms of refugee protection dating to World War II. Why else choose the two countries that have repeatedly been singled out for violating the rights of refugees?

As in Israel and the U.K., there will be court challenges should the U.S. move forward with its proposed plan of sending migrants to Libya and Rwanda. It is hard to imagine a court that could rule that the U.S. would not be in breach of its legal obligation of nonrefoulement by delivering migrants to these two countries.

Having said that, and despite the clear language of the treaty and statute, it has become increasingly difficult to predict how the courts will rule when the Supreme Court has issued decisions overturning long-accepted precedent, and lower courts have arrived at diametrically opposed positions on some of the most contentious immigration issues.

In times like these, we should not depend solely on the courts. There are many of us here in the U.S. who believe that the world’s refugee framework — developed in response to the profound moral failure of turning back the St. Louis — is worth fighting for. We need to take a vocal stand. The clear message must be that those fleeing persecution should never be returned to persecution.

If we take such a stand, we will be in the good company of those who survived the Holocaust and continue to speak out for the rights of all refugees.

Karen Musalo is a law professor and the founding director of the Center for Gender and Refugee Studies at UC Law, San Francisco. She is also lead co-author of “Refugee Law and Policy: A Comparative and International Approach.”