<Table> <Tr> <Th_colspan="2"> Nuclear tests </Th> </Tr> <Tr> <Th_colspan="2"> Information </Th> </Tr> <Tr> <Th> Country </Th> <Td> North Korea </Td> </Tr> <Tr> <Th> Test site </Th> <Td> Punggye - ri Nuclear Test Site, North Korea </Td> </Tr> <Tr> <Th> Period </Th> <Td> 2006--present </Td> </Tr> <Tr> <Th> Number of tests </Th> <Td> 6 </Td> </Tr> <Tr> <Th> Test type </Th> <Td> underground </Td> </Tr> <Tr> <Th> Max . yield </Th> <Td> <Ul> <Li> ~ 140 kt (U.S. intelligence) </Li> <Li> 160 kt (Revised estimates from Japanese Government) </Li> <Li> 250 kt (38 North and revised NORSAR estimate) </Li> </Ul> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Nuclear tests </Th> </Tr>

Where does north korea test its nuclear weapons