United States Government/Foreign Policy
This definition of war is problematic. Typically a declaration of war can only be made between nations, states, or specific entities. War is also understood as the continuation of policy by other means, so labeling an actual policy as war seems to indicate the refusal to come to any political understanding about the subjects in question.
North Korea (China)
Respecting a ceasefire of the Korean War since 1953. Both Koreas are still technically at war and so by proxy it constitutes an ongoing war between China and the United States.
War on Drugs (South America)
War on Terrorism
The USA has also declared itself to be to fighting a "war on terrorism". This bring to the table the concept of "terrorism" and "terrorist", there is no internationally agreed definition of terrorism. But the term imparts a negative light on an opposing group. On the other end of the spectrum it would be the label of "resistance", "freedom fighters", etc.
A more neutral definition would be "violent non-state actor", meaning a group constituted by irregular forces, with typically no formal organization, that is engaged in asymmetric and clandestine paramilitary operations against a given state or state interest.
A declaration of war in these terms cannot be formally made. As such a statement that there is a "war on terrorism" is insufficient to clearly define what the USA policy on terrorism actually is. It can reasonably be inferred from current behavior that this one sided state of open, armed and prolonged conflict, not against all "terrorists groups" as the USA is only taking action against groups that block or create difficulties to its national interests. This also makes it extremely hard to define the achievement of goals and creates an impossibility to reach a status of submission from the opposing forces.