I want to load data from an external file into a Teradata table and restrict the data to only those records that already exist in a previously loaded Teradata table.

For example; I have two files:

FileA
F1 F2 F3
AAA,USA,1
BBB,CAN,2
CCC,RUS,3

FileB
F3 F4
1,FRANK
2,BILL
3,JIM

I want to load FileA into TableA but restrict it to just USA records.
Then I want to load FileB into TableB but only load records where field F3 in FileB already exists in field F3 in TableA that was loaded in the prior step.

After both tables are loaded I should have just the following:
TableA
F1 F2 F3
AAA USA 1

TableB
F3 F4
1 FRANK

How do I do this in MLOAD?