...the treaty between the United States and Pakistan contains no provision that bars forcible abductions, nor does it otherwise 'purport to specify the only way in which one country may gain custody of a national of the other country for the purposes of prosecution.' Id. at 664. Nor does the treaty provide that, once a request for extradition is made, the procedures outlined in the treaty become the sole means of transferring custody of a suspected criminal from one country to the other.