In Yemen Saudi Arabia now faces pushback from eastern tribe

Saudi Arabia's venture into Yemen to try and reinstate the internationally recognized government of Mansur Hadi has caused the country continual problems as it has confronted not just Houthi rebels who control much of the north but southern separatists.

The Southern Transitional Council(STC), separatists fighting for an independent South Yemen, with the help of United Arab Emirates (UAE) forces had seized the southern port of Aden and some surrounding areas. However, the Saudis were able to reach a peace agreement with the STC and the UAE giving the STC some seats in the Hadi government but much to Hadi's displeasure.
Now it appears the Saudis may be creating a new enemy apart from the Houthis who control much of the north and are supported by Iran. The Saudis stormed the town of Shahn in the east of the country on the Oman border.
The Saudi attack
The Saudis have not explained what their aim was but they attacked a cargo port that belongs to the Mahra tribes in Mahra Province. The province has seen almost no fighting since the 2015 Saudi invasion. It is far east of Houthi-controlled territory. Mahra tribesmen denounced the seizure as a Saudi intrusion and claimed the seizure of the port was a violation of the sovereignty of the tribe. Saudi forces had opened fire during the seizure and injured a number of fighters.
A people's sit-in committee of the Mahra tribe issued a statement on Facebook: "The committee condemns these practices and violations committed by the Saudi occupation and its militias against our people. It constitutes a flagrant violation of Yemeni sovereignty and national identity. In this dangerous turning point of our honorable history, we call on all the tribes of the province, their sheikhs and their dignitaries, and their citizens to unite alongside all the liberals of the province to prevent the Saudi occupation from imposing its domination Al-Mahra."
Starting a fight with the tribes is a risky move as tribal factions and alliances in Yemen have often been more powerful than the government. The Saudis could be in for a fierce fight on territory where before there had been no resistance to the Saudi invasion.
The apparent reason behind the seizure
Saudi Arabia has already stationed some troops in the province. They have taken control of the airport and the main seaport. They did so after alleging that they were important points for smuggling weapons to the Houthis who control much of the northeast of Yemen including the capital Sanaa. The Saudis have also established more than a dozen military bases in the province and this has led to frequent tensions which have been escalating into armed clashes. It looks as if the Saudis are creating new enemies even while they appear unable to drive back the Houthis.
War has created a humanitarian disaster and caused many casualties
A Saudi-led coalition has been fighting Houthi rebels since 2015. Saudi actions have been widely condemned as they have targeted schools and hospitals, and even a wedding party. Including civilians and fighters some reports estimate that over 100,000 people have been killed since the war started. As mentioned earlier the Saudi coalition has been trying to restore the internationally-recognized government of Mansur Hadi but so far have not been able to retake the north and the capital from the Houthis,
The fighting has left millions suffering from food and medical shortages creating what many claim is the world's worst humanitarian disaster. As shown in the appended video the Houthis claim to have shot down a plane.