Sun Tzu and Clausewitz had differing views on the proper role of the diplomat in war. Sun Tzu argued that "All warfare is based on deception," explaining, "when able to attack, we must seem unable; when using our forces, we must seem inactive...Attack him where he is unprepared, appear when you are not expected" (Szykman). Sun Tzu contends for an indirect approach and says that although "the direct method may be used for joining battle," it is the indirect methods that are necessary to "secure victory" (Szykman). Examples of indirect methods include looking disorganized but being greatly organized underneath, pretending to be afraid, "keeping the enemy on the move," and manipulating the opponent through the use of bait (Szykman).
Clausewitz agreed with Sun Tzu's assertion that deception is necessary. His contentions that "War is the province of uncertainty" and "The aim of war is to disarm the opponent" are similar to Sun Tzu's indirect deceptive methods ("Clausewitz and Terrorism," 2003). Clausewitz also, however, advocated attacking the enemy's finances, stores, supply routes, and training establishments ("Clausewitz and Terrorism," 2003).
Both philosophers make good points, and ultimately it is probably necessary to follow the advice of both in a really difficult wartime situation. The major difference between the two is that Sun Tzu advocates evading and tricking the enemy while Clausewitz advocates attacking. The former's approach is best for situations where one is outnumbered by the enemy, and the latter's approach is best where one has the stronger position in terms of force and manpower.
"Clausewitz and Terrorism." Everything2.com. 2003. Szykman, Simon. "The Art of Diplomacy in The Art of War." The Zine.