The NSA bugged the UN’s New York headquarters, Germany’s Der Spiegel weekly said on Sunday in a report on U.S. spying that could further strain relations between Washington and its allies, Reuters reports. Citing secret U.S. documents obtained by fugitive former intelligence contractor Edward Snowden, Der Spiegel said the files showed how the U.S. systematically spied on other states and institutions. In three weeks, according to the weekly, the NSA increased the number of decrypted communications at the U.N. from 12 to 458, reports the Washington Post.  Snowden’s leaks have exposed details of the United States’ global surveillance apparatus, sparking an international debate over the limits of American spying. Meanwhile, Sen. Bob Corker, the top Republican on the Senate Foreign Relations Committee, told Chris Wallace of Fox News Sunday, even he doesn’t know the extent of NSA’s surveillance.