Two other sitting U.S.presidents have become Nobel laureates: Woodrow Wilson and Theodore Roosevelt.

VOA: standard.2009.10.09

The official list of confirmed attendees provided by the British prime minister's office as of Tuesday afternoon didn't include any senior currently serving members of the current U.S. administration or current or former U.S. presidents.

WSJ: Global Figures Pay Respects at Funeral for Margaret Thatcher in London

In recent years, former U.S. presidents have traveled to North Korea to secure the release of detained U.S. citizens.

WSJ: North Korea Sentences U.S. Citizen to 15 Years Hard Labor

He is expected to invite former U.S. presidents as well as members of Congress to accompany him in a U.S. delegation.

CNN: Rabin seen as 'a great hero'