"With appropriate diplomatic pressure, these governments may cooperate in bringing Assange to justice. But if they refuse, the United States can arrest Assange on their territory without their knowledge or approval. In 1989, the Justice Department's Office of Legal Counsel issued a memorandum entitled "Authority of the Federal Bureau of Investigation to Override International Law in Extraterritorial Law Enforcement Activities."
This memorandum declares that "the FBI may use its statutory authority to investigate and arrest individuals for violating United States law, even if the FBI's actions contravene customary international law" and that an "arrest that is inconsistent with international or foreign law does not violate the Fourth Amendment." In other words, we do not need permission to apprehend Assange or his co-conspirators anywhere in the world.
Arresting Assange would be a major blow to his organization. But taking him off the streets is not enough; we must also recover the documents he unlawfully possesses and disable the system he has built to illegally disseminate classified information.
This should be done, ideally, through international law enforcement cooperation. But if such cooperation is not forthcoming, the United States can and should act alone. Assange recently boasted that he has created "an uncensorable system for untraceable mass document leaking." I am sure this elicited guffaws at the National Security Agency. The United States has the capability and the authority to monitor his communications and disrupt his operations.""