The title says it all.
Can be clearly seen for example in this image:
(image source: Wikimedia)
The rest of the jet seems to have a camouflage.
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It is all part of the camouflage.
The blue parts on the bottom make the aircraft hard to identify from below against a blue-background (sky). The dark parts on the top make it difficult to identify from above against a dark background (ground).
The white parts make the aircraft's size/shape difficult to determine. This helps to confuse the enemy by making the aircraft seem farther away than it really is.