Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) If President-elect Donald Trump decides to make good on his campaign pledge to "load up" the prison camp in Guantanamo Bay, Cuba, with new domestic terror suspects caught in the US -- including American citizens -- legal experts say he is asking for an unprecedented constitutional showdown. Voters first received a peek at Trump's stance on Guantanamo Bay back in 2015 when talking points on various policy questions were leaked ahead of a Republican debate. On the issue of whether he would close the detention facility, the memo stated: "No. I would also take away the passports of Americans who fight for ISIS and send them to Gitmo for some R&R."The prison at Guantanamo Bay opened its doors in 2002 and currently houses 60 detaineesNo American accused of terrorist activity on US soil has ever been held at Guantanamo Bay 
 Question:National security experts outside of Trump's inner circle, however, said he will face a different reality once he becomes president and discover the unique challenges posed by _.

Guantanamo Bay