Are basic arithmetic operations in a C # atom

Are basic arithmetic operations safe for threads?

For example, if there is a function ++for a global variable that will be changed from different threads, is it necessary to block it?

for instance

void MyThread() // can have many running instances
{
    aGlobal++;
}

or should he be

void MyThread()
{
    lock( lockerObj)
    {
        aGlobal++;
    }
}