It's not that simple. There's no uniform definition of strong. You're right strong typing is often used to refer to absence of (or restrictions to) implicit type conversions, but it has also since the beginning been used to reference languages that does not prevent obscuring the identity of the type of an object.

E.g. Liskov and Zilles [1] defined it this way for example:

"whenever an object is passed from a calling function to a called function, its type must be compatible with the type declared in the called function."

Under this definition C and C++ fails hard, since you can statically cast a pointer to an object and pass it to a function expecting a totally incompatible type.

Note that the system described relied at least partly on dynamic/runtime type checks (in case it reads as if the quote above suggests they used "strong" to refer to static typing):

"It is desirable to do compile-time type checking, since type errors are detected as early as possible. Because of the freedom with which types can be used in the language, however, it is not clear how complete the compile time type checking can be. Therefore, the design of the language is based on a runtime type checking mechanism which is augmented by as much compile-time checking as is possible. "

[1] https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.13...