Not running TO the UN. Just reminding you that we promised, along with all other members, not to start wars. No matter what you think of the UN bureacratic organization, that provision is a good idea. It tends to prevent wars.
It makes the US invasion of Iraq illegal. The invasion was also weakining in that we have tied up major resources there, not fighting the War on Terror but helping Al Queda in its recruiting efforts. This makes us less able to handle whatever else might come up in the next few years, till we get loose of that tiger.