The latest move in an increasingly hostile back-and-forth: North Korea has cut off all ties with South Korea after accusing its navy of trespassing in its waters over the course of the past few weeks, and is threatening military retaliation. An announcement reportedly read, "This is a deliberate provocation aimed to spark off another military conflict in the West (Yellow) Sea of Korea and thus push to a war phase the present North-South relations that reached the lowest ebb," adding that if the supposed trespassing continues North Korea "will put into force practical military measures to defend its waters [...] and the South side will be held fully accountable for all the ensuing consequences." The accusation comes after South Korea instituted a trade ban against North Korea, a reaction to the sinking of one of its warships in March. The conflict has caused Asian markets to falter and Secretary of State Hillary Clinton grimly assessed the situation as a "serious challenge."