Under both US law and international law, anyone who seeks asylum at a port of entry into the United States must be received, allowed to request asylum, and referred to an asylum officer for the of review their claim.
Turning these people away from the border would mean that US authorities were breaking the law.
No border wall will be effective as long as the invaders can ask any USCIS person at any port of entry for asylum and Article 23 welfare benefits and lightning fast Article 34 naturalization to start the chain migration process for their relatives.
The Republican Congress needs to denounce [get out from under] the Refugee Convention.
Article 44 denunciation
1. Any Contracting State may denounce this Convention at any time by a notification addressed to the Secretary-General of the United Nations.
2. Such denunciation shall take effect for the Contracting State concerned one year from the date upon which it is received by the Secretary-General of the United Nations....
Asylum laws are different than immigration laws.