Saudis brag, but US denies they ever sent warnings about Boston Marathon

"... The news of more arrests came after it emerged Saudi Arabia reportedly sent a written warning to the US about Boston Marathon suspect Tamerlan Tsarnaev last year and refused him entry to the country over security concerns.
The Kingdom of Saudi Arabia wrote to the US Department of Homeland Security about the older Tsarnaev brother in 2012, a senior Saudi official says....
The Saudi official said the warning, which was also shared with the UK Government, was "very specific" and warned "something was going to happen in a major US city"....
An official from Homeland Security denied the department had received any such warning from Saudi Arabia.
"DHS has no knowledge of any communication from the Saudi government regarding information on the suspects in the Boston Marathon Bombing prior to the attack,"..."