What Trump said on immigration at the UN wasn't a "dogwhistle" but a clarion call:

It has been the formal policy of our country since President Monroe that we reject the interference of foreign nations in this hemisphere and in our own affairs. The United States has recently strengthened our laws to better screen foreign investments in our country for national security threats, and we welcome cooperation with countries in this region and around the world that wish to do the same. You need to do it for your own protection.

The United States is also working with partners in Latin America to confront threats to sovereignty from uncontrolled migration. Tolerance for human struggling and human smuggling and trafficking is not humane. It’s a horrible thing that’s going on, at levels that nobody has ever seen before. It’s very, very cruel.

Illegal immigration funds criminal networks, ruthless gangs, and the flow of deadly drugs. Illegal immigration exploits vulnerable populations, hurts hardworking citizens, and has produced a vicious cycle of crime, violence, and poverty. Only by upholding national borders, destroying criminal gangs, can we break this cycle and establish a real foundation for prosperity.

We recognize the right of every nation in this room to set its own immigration policy in accordance with its national interests, just as we ask other countries to respect our own right to do the same—which we are doing. That is one reason the United States will not participate in the new Global Compact on Migration. Migration should not be governed by an international body unaccountable to our own citizens.

Ultimately, the only long-term solution to the migration crisis is to help people build more hopeful futures in their home countries. Make their countries great again.