It is very ironic that during the Obama years, when States tried to protect their own borders, they were shot down because, the courts said, security is the responsibility of the Federal Government. Yet, now we have President Trump taking responsibility for security and they are arguing that it is the right of the states.
It seems like this is a basic question that must be settled. When you look up "duties of the executive branch" every sites says: "Enforcing the laws of the United States". Obama was correct that it was not the state's right, problem was, he wouldn't do it. Now we have a President who will do his job. We have immigration laws. It is up to the President to enforce them or up to Congress to change them.
