Some of the underlying tension between Saudis and Qatar (FWIW, over a decade ago when I was last at Al Udeid, the Al Thani family leader (previous Emir to this one) was considered by many to be (as Arab heads of state go) fairly progressive).
(
SOURCE) Qatar also gradually eclipsed Saudi Arabia as a regional leader entrusted to resolve civil disputes, frequently hosting warring factions from Afghanistan, Sudan, Lebanon, and the Palestinian territories for reconciliation talks.
At other times, Qatar supported the emergence of alternative centres of power around the region, launching the Al Jazeera network in 1996 with the aim of bringing to light views that had been largely suppressed by regional dictatorships, including those of the Islamist opposition.
Most of the current accusations against Qatar date back to the years leading up to and during the Arab Spring uprisings that began in 2010. Unlike its neighbours, Qatar lent its support for the removal of authoritarian regimes in Egypt and Tunisia, and generally endorsed the possibilities offered by a new era of political openness for repressed populations around the region.
That support was quite often channelled through Islamist parties poised to take power in democratic elections such as the Muslim Brotherhood in Egypt and the Ennahda Movement in Tunisia. Even amid questions surrounding Qatar's actual motives for pursuing such a policy, or the fact that it stopped short of supporting the uprising in neighbouring Bahrain, Qatar was placed in the anti-establishment camp
Another look at this, in part
(
Source is PhD candidate/political analyst at U of Maryland, College Park, which is just outside of Washington DC).
While the two countries {Saudi/Qatar} were able to contain their policy differences through diplomatic means for the better part of the four decades since the establishment of the Gulf Cooperation Council's (GCC), there have been previous precedents to the current Riyadh-Doha rift.
In 1992, for example, the two neighbours had a border skirmish. More recently, Saudi Arabia, along with United Arab Emirates (UAE) and Bahrain, withdrew its ambassador from Doha back in 2014.
But it is also necessary to evaluate the US' position in the region. Qatar, after all, is the home of the largest US military base in the region. I think the Trump administration is implicitly pleased to see the Qataris sweat this crisis out. From Washington's point of view, this crisis may help Doha to fully understand the importance of the American presence, and to modify some of its regional policies that are not aligned with US interests.
In the American capital, some view Doha's support for political Islam to be at odds with its relations with the United States. Only hours after Riyadh and UAE's announcement about severing ties with Doha, US Secretary of State Tillerson stated that he "encourage[s] the parties to sit down together and address these differences … it is important that the GCC remain unified".
It would be safe to say that a military activity on the Qatari-Saudi border is highly unlikely, and it would constitute a red line for the Pentagon. Also, the US government will not allow Doha to fall out of the American sphere of influence.