Having set the rhetorical bar high during his campaign, President Trump has taken several steps attempting to make good on his promise to restrict immigration. Arguably, the most controversial of those – “The Wall” notwithstanding – is his executive order to ban U.S. entry to travelers, including refugees, from six Muslim-majority nations: Yemen, Syria, Sudan, Somalia, Iran and Libya.

The ban for travelers would be in effect for 90 days – 120 days for refugees – while the government reviews possible improvements in vetting procedures. Immigrants from these six counties working in the U.S. under H-1B visas need not worry about deportation — or the travel ban — though immigration lawyers advise against leaving the country until the conditions of the ban are changed or lifted entirely.

Since announcing the order, the 4th U.S. Circuit Court of Appeals invoked a freeze on the ban – deeming it discriminatory – and the decision was upheld by the 9th Circuit Court. Now, the Trump administration has asked the U.S. Supreme Court to allow the ban to go into effect.

While this life-and-death refugee drama continues to play out domestically, the proposed ban may well face another problematic challenge: it appears to violate several international treaties ratified by the United States. Following the massive displacement of populations as the result of World War II, the Refugee Convention of 1951 was ratified by 145 State parties, defining the term “refugee” as well as the legal obligations of States to protect them.

Further, the 1967 Protocol Relating to the Status of Refugees, an update to the Refugee Convention, prohibited discrimination on the basis of race, religion or national origin. Some of the provisions of these agreements have even been incorporated into U.S. law and cited as binding by the United States Supreme Court.

Steffen Seibert, spokesperson for German Chancellor Angela Merkel, said in a statement, “The Geneva Refugee Convention requires the international community to take in war refugees on humanitarian grounds. All signatory states are obligated to do (so)…She (Merkel) is convinced that the necessary, decisive battle against terrorism does not justify a general suspicion against people of a certain origin or a certain religion.”

Meanwhile, ironically, the executive order cannot displace domestic legal obligations. So those who do manage to reach U.S. soil claiming asylum will have to have their claims examined. The duty not to return a person to a state where they may face torture or other serious harm is absolute under the UN’s Convention Against Torture – which the United States has signed and ratified.

Of course, the question of whether the ban violates international law will only come into play should the Supreme Court decide in favor of the administration. Then, if Trump forges ahead, will the international community attempt to “punish” the U.S. or, if unwilling to do so, will they make plans to increase their own refugee resettlement programs?

Only time will tell.