SEOUL (AFP) — North Korean jet fighters have tested South Korean defences by flying near the border repeatedly in the past month, prompting Seoul to scramble aircraft in response, news reports said Monday.Seoul military authorities refused comment on the reports, which comes amid a flare-up in tensions between the two nations. On Sunday the communist state's official media claimed that Seoul is planning a preemptive military strike and threatened to turn South Korea into "ashes" if it went ahead. In the past five days the North has expelled South Korean officials from a joint industrial complex, test-fired missiles, accused Seoul...