Isolate IP access to USA controlled IP address
 

Goto CP and "User Ban Options" add the following IP addresse blocks:

The following basically restricts the access to only ARIN administrated IP addresses only. NO RIPE or APNIC... etc..

58.*.*.*
59.*.*.*
60.*.*.*
61.*.*.*
62.*.*.*
76.114.*.*
77.*.*.*
78.*.*.*
79.*.*.*
80.*.*.*
81.*.*.*
82.*.*.*
83.*.*.*
84.*.*.*
85.*.*.*
86.*.*.*
87.*.*.*
88.*.*.*
89.*.*.*
90.*.*.*
91.*.*.*
92.*.*.*
93.*.*.*
94.*.*.*
95.*.*.*
109.*.*.*
110.*.*.*
111.*.*.*
112.*.*.*
113.*.*.*
114.*.*.*
115.*.*.*
116.*.*.*
117.*.*.*
118.*.*.*
119.*.*.*
120.*.*.*
121.*.*.*
122.*.*.*
122.*.*.*
123.*.*.*
124.*.*.*
125.*.*.*
126.*.*.*
178.*.*.*
189.*.*.*
190.*.*.*
188.*.*.*
186.*.*.*
187.*.*.*
183.*.*.*
180.*.*.*
124.*.*.*
192.*.*.*
193.*.*.*
194.*.*.*
195.*.*.*
196.*.*.*
197.*.*.*
198.*.*.*
200.*.*.*
201.*.*.*
202.*.*.*
203.*.*.*
210.*.*.*
211.*.*.*
212.*.*.*
213.*.*.*
217.*.*.*
218.*.*.*
219.*.*.*
220.*.*.*
221.*.*.*
222.*.*.*

http://www.iana.org/assignments/ipv4-address-space/