Which is why they apply for asylum, a process enshrined in the US Code.
8 U.S. Code § 1158. Asylum
Any alien who is physically present in the United States or who arrives in the United States (whether or not at a designated port of arrival and including an alien who is brought to the United States after having been interdicted in international or United States waters), irrespective of such alien’s status, may apply for asylum in accordance with this section or, where applicable, section 1225(b) of this title.
8 U.S. Code § 1158. Asylum Any alien who is physically present in the United States or who arrives in the United States (whether or not at a designated port of arrival and including an alien who is brought to the United States after having been interdicted in international or United States waters), irrespective of such alien’s status, may apply for asylum in accordance with this section or, where applicable, section 1225(b) of this title.
=https://www.law.cornell.edu/uscode/text/8/1158