How do you define internationalism and multilateralism?
Internationalism has two faces.
Its pleasant face emphasizes mutual cooperation, treaties and standards of mutual benefit, an orderly flow of trade, and cooperation instead of conflict.
However, its other face is vile. Based on the idea that nations, languages, cultures and ethnic groups are obsolete, and should be normalized into administrative districts within trading blocs and world government. That is, nations should just be districts with open borders, and the rest should be homogenized with immigration until they cease to exist.
Its overriding impulse is the belief that human differences are responsible for war, so that if such differences are systematically erased, generic humanity will be at ease under a single government.
The primary political organization hoping to achieve this is the international socialist movement, with entire leftist political parties around the world as its membership. It has grown to include more than 150 member parties from more than 100 countries. Its members have governed in many countries including most of Europe.
http://en.wikipedia.org/wiki/Socialist_international
Two sitting justices on the Supreme Court of the United States have embraced the idea that federal court decisions should include foreign legal ideas, but couched in American terms, using our judicial precedents.
Many members of congress, mostly Democrats but including some Republicans, have embraced some of the ideas of internationalism. George W. Bush was a firm believer in much of it, and made several strong, if ineffective efforts on its behalf. Bill Clinton also believed in it.
The bottom line is that it is anti-American, in any form, and while those who embrace it may seek to pursue its pleasant face, the two faces are inexorably linked.
It is a deal with the devil himself.