@jwcph
I'd start with getting a clearer definition of "too many"

"National coherence"is a strange phrase - As I was growing up (1960s) the phrase"melting pot" was hailed as a virtue - and we had many different cultures within the US, with strong regional character. (We still do - and many are not immigrant cultures) And we celebrated the various cultures. The national "we" at least preached aspirational goals (and yes, we fell far short in many cases).

And that national "We" was made up of people from many backgrounds, often informed by their religion &/or the countries they or their foreparents came from - so these cultures differed from one another, and evolved as they overlapped in various ways.

I've known, and in many cases worked with, immigrants from many places - China, Iran, Iraq, Somalia, Mexico, Guatamala, Pakistan, India, Italy, Germany, Syria. Almost all of them want to integrate in the US culture, to be part of the larger community. We need to work on enabling that integration.