'Save the Date' faxes for the royal wedding were sent out to guests around the globe on Tuesday, but the fax machine at the White House wasn't buzzing with a letter from the Queen of England.

While the former Greek monarch and Serbia's Crown Prince both confirmed that they had gotten the royal note, President Barack Obama and wife Michelle have been 'snubbed' from the guest list of the decade.

But Royal expert Roy Sheppard told Breaking Celebrity News that the first family most likely got the cold shoulder because of security reasons, not because of a social faux pas.

"I would assume that the cost of the Obama security would be unbelievably high and the bill would be sent to the royal family," explains Sheppard.

Prince William is not yet heir to the throne so his and Kate's wedding on April 29th isn't a state occasion that would justify the cost of the President and his massive security detail attending.

"It's a private event even though hundreds of millions of people will watch it, and the royals - and British taxpayers - would have to pay for the p