Okay, here's part of the problem with national interest (you could have figured this out yourself): my national interest sometimes infringes on your national interest. So who has right of way? Refer to Nietzsche: whoever has the will to power.
That's part of what we're looking at in Israel right now. Two (ostensibly) national interests that don't taste great together.
And our unilateral pursuit of our national interest has given everyone precedent to pursue theirs.
See the problem?