new and delete handles multithreading issues-Collection of common programming errors

I am reading a book Efficient C++: Performance Programming Techniques Authors is saying following regarding global new and delete operators:

They manage memory in the process context, and since a process may spawn multiple threads, new() and delete() must be able to operate in a multithreaded environment. In addition, the size of memory requests may vary from one request to the next.

in Chapter 6. Single-Threaded Memory Pooling.

Is this true? I thought C++ does not have a notion of a Multi-threading environment, programmer need to handle is by using some means of mutual exclusion.