The summit is come to be seen as a significant part of the 'war against terror' in US. This is especially true in the case of Afghanistan as US is sending thousands of troops this summer to fight the Taliban.
Pak president and Afghan president are expected to land in Washington on Tuesday, May 5. Due to 'alarming security situation' in the country, Pak Army Chief General Ashfaq Pervez Kayani will not accompany Zardari.
Obama will initially be meeting the two leaders separately following which he would be meeting both the leaders together in the trilateral meeting.