"First of all I am very pleased the police were able to apprehend him and now he is rightly behind bars because he broke UK law," Javid told BBC Radio 4 on Thursday.
"There is an extradition request from the US that is before the courts tomorrow but yesterday I signed the extradition order and certified it and that will be going in front of the courts tomorrow," he added.
The US will detail all charges against Assange on Friday, when it seeks his extradition in a London court.