The rift between Qatar and other Arab nations intensified Monday whenSaudi Arabia closed its land border with Qatar and at least five Gulf-based airlines announced they will halt service to the desert peninsula nation.

Saudi Arabia, a Sunni-dominated nation, has long had tense relations with Shiite Iran and has developed a “Sunni coalition” in the region to curb Iran’s influence. The U.S. supports the Saudi effort. Qatar is predominantly Sunni and is a member of the coalition but has close economic ties with Iran, including sharing a major offshore gas reserve.

Last week, Qatari Emir Tamim bin Hamad Al Thani roiled the Saudis when he phoned Iranian President Hassan Rouhani with congratulations on his re-election.

Saudi Arabia, Egypt, the United Arab Emirates, Bahrain and Yemen cut ties to Qatar on Monday, claiming the energy-rich monarchy is undermining stability in the region by supporting in the Iran-aligned militant groups. Authorities gave Qataris living in and visiting their countries two weeks to leave.

more:   http://www.cnbc.com/2017/06/05/why-saudi-arabia-is-mad-at-qatar-and-why-we-care.html