If a person arrives on US soil and claims asylum, does the US have to deal with their claim under international law? Yes. Not only does the US have an international legal obligation to do so, based on the requirement of complying with the object and purpose of the 1951 Refugee Convention, and implementing legal obligations in good faith, it has an obligation to do so under its own domestic law.
The executive order cannot displace domestic legal obligations. So those who, with great difficulty, manage to reach the US will have to have their asylum claims examined. The duty not to return a person to a state where they may face torture or other serious harms is absolute under the UN’s Convention Against Torture. The US has signed and ratified this convention.
However, with the likely increase in asylum detention of people crossing the US-Mexico border that will arise from one of Trump’s earlier executive orders, there is potential for decisions on whether a person is a refugee being made in an exceptionally tight time frame. It’s possible that, more generally, asylum decisions will be rushed through and the law not properly adhered to.
Under international law, can the US ban asylum seekers from certain countries?
Under international law, the US cannot ban asylum seekers from certain countries. The US has signed and ratified a number of international treaties that prohibit religious and race discrimination in the operation of legal systems, and this extends to operating a migration system in line with international non-discrimination protections.