What does ‘unbelievably small’ mean?

The trouble with John Kerry is that he is clearly in love with his own voice and does not know when to stop talking. While in the senate, he was notorious for long droning speeches at committee hearings that often resulted in him running out his allotted time before he could ask questions of the people before the panel. The Daily Show lampooned his performances back in 2009.

(These clips aired on January 14, 2009 and October 27, 2009 respectively. To get suggestions on how to view clips of The Daily Show and The Colbert Report outside the US, please see this earlier post.)

Kerry’s habit of talking long after he has had anything useful to say invariably results in him talking nonsense. While this was not a problem in the US senate where nonsense is the norm, it is a problem when he is the Secretary of State and the rest of the world looks to his words for cues about US policy. His habit of saying things that have to be immediately clarified bu aides or are contradicted by president Obama is not the stuff of good diplomacy.

He now says, apropos Syria, that the proposed US attacks would be “unbelievably small”, a statement that has infuriated those who love nothing better than to see massive destruction on yet another Arab country. He presumably meant that the military attack would be brief but ‘unbelievably small’ makes no sense. Not believable by whom?