Political considerations only apply when the attacker has a use for you where politics are a factor. But in a case of a war of annihilation -or any other conflict where subjugation/eradication of the enemy is the ultimate goal and the ideological differences are great enough that a diplomatic agreement cannot be reached- targeting leaders is usually counter-productive.
In a major conflict, you seek to do the greatest damage possible, with the fewest options of recovery for the enemy, for the minimum possible expense. If you want to really make your point, you don't bother assassinating an enemy leader where he can become a martyr and other leaders get to be elected. You bomb a few nuclear power plants and let the enemy deal with the massive fallout. You explode a gigaton-level nuke in the Earth's magnetic "shields" over the enemy's country, the resulting EMP frying unshielded devices over half the continent. You unleash a bioweapon tailored for the enemy nation's specific genetic identity on a few major airports.
Regarding the way Supers can change such a war, here's a PL10 paragon of mine;viewtopic.php?f=20&t=42799&p=923099#p923099
If you take her to a normal battlefield, she's only as powerful as a battleship or so. But why would a Superman-type character (even a relatively low-powered one) allow herself to be engaged via conventional forces at all? She flies to mid-orbit and starts frying enemy sattelites one by one. Within the hour, the enemy's long-range strategic and tactical networks are down.
Then she flies into the stratosphere and begins long-range dismantelement of enemy assets. Even with a Rank 10 speed, a typical paragon or speedster can double-move at Mach 6. There's no current tech projectile weapon that can shoot her at that speed; bullets are at most mach 2, and even anti-air missiles are Mach 5. With Rank 12 speed, she double-moves at Mach 24 so you can just forget about it.
For the real kicker, she picks up big rocks, flies them into orbit then lets them drop onto enemy cities. A rock free-falling for 20 minutes under slightly less than 1 g acceleration will hit at over 5 miles per second. It will impact with the same explosive force as ten times its mass in TNT. So a rock 25 ft across (1000 tons) hits with about the explosive energy of the Hiroshima bomb if it falls from orbit. A typical paragon can lift that much into orbit. This gal can lift 25 thousand tons, resulting in 1/4 megaton impacts. Superman could lift 400 thousand tons -sixteen times as much-, resulting in 4-megaton impacts.
A single Paragon with 1/16 the power of Superman could beat a current world "superpower" country in a day.
Now imagine a few dozen of those guys and gals fighting on each side of the war.