From the US view:
FM 1-02 Operational Terms and Graphics
operational art – (DOD) The employment of military forces to attain strategic and/or
operational objectives through the design, organization, integration, and conduct of
strategies, campaigns, major operations, and battles. Operational art translates the joint
force commander’s strategy into operational design, and, ultimately, tactical action, by
integrating the key activities at all levels of war. See also strategic level of war; tactical
level of war. See FM 3-0.
operational level of war – (DOD) The level of war at which campaigns and major operations
are planned, conducted, and sustained to accomplish strategic objectives within theaters or
operational areas. Activities at this level link tactics and strategy by establishing operational
objectives needed to accomplish the strategic objectives, sequencing events to achieve the
operational objectives, initiating actions, and applying resources to bring about and sustain
these events. These activities imply a broader dimension of time or space than do tactics;
they ensure the logistic and administrative support of tactical forces, and provide the means
by which tactical successes are exploited to achieve strategic objectives. See also strategic
level of war; tactical level of war. See FM 3-0.
strategic level of war – (DOD) The level of war at which a nation, often as a member of a
group of nations, determines national or multinational (alliance or coalition) strategic
security objectives and guidance, and develops and uses national resources to accomplish
these objectives. Activities at this level establish national and multinational military
objectives; sequence initiatives; define limits and assess risks for the use of military and
other instruments of national power; develop global plans or theater war plans to achieve
these objectives; and provide military forces and other capabilities in accordance with
strategic plans. See also operational level of war; tactical level of war. See FM 3-0.
tactical level of war – (DOD) The level of war at which battles and engagements are planned
and executed to accomplish military objectives assigned to tactical units or task forces.
Activities at this level focus on the ordered arrangement and maneuver of combat elements
in relation to each other and to the enemy to achieve combat objectives. See also
operational level of war; strategic level of war. See FM 3-0.
Basically anything that is controlled by a Division HQ or lower is Tactical.