Here, we are first using the numpy.random.randint() function to create an nxn square matrix that contains random integers. The generated integers will be within the range [low, high). And the size argument specifies the size of the matrix. For example, size=(n, n) specifie that the created matrix will have n rows and n columns.

Now, we are using the numpy.triu() function to generate an upper triangular matrix from A. The argument k=0 specifies that the generated matrix U will have all the elements below the principal diagonal zeroed. And the elements across and above the principal diagonal will be copied from A to the created upper triangular matrix.

The output of the mentioned program will be:

A: 
 [[9 1 2]
 [1 2 3]
 [9 8 9]]
The Upper Triangular Matrix U: 
 [[9 1 2]
 [0 2 3]
 [0 0 9]]