There is no such thing as man made climate change.
The climate does change and is probably on a grand scale beyond our grasp as to how the world climate cycle works between ice ages and dust bowls. The earth could be on a ten thousand year cycle of repeating events that we would be clueless on.
If we had weather change could that be a national security threat? I would think it is possible in as much as having a mini ice age on the states could effect security.
Right- the Chinese and Russian armies could walk right across the frozen straits to Alaska!