Pro-government and Southern Transitional Council forces began a gradual withdrawal on Tuesday in the provinces of Shabwa and Abyan in line with the terms of an agreement struck late last year in Riyadh to ease tensions in Yemen’s south. Over the summer, the STC and government clashed in several areas of the south after a dispute over security and the involvement of some elements in the government. The tensions ended with a deal brokered by Saudi Arabia and backed by the UAE that culminated with the signing of the Riyadh Agreement in November that, among other things, would see a shake-up of the Yemeni cabinet and military forces pull back to previous positions. A military source in the STC forces told <em>The National</em> that their 9th shock brigade had begun a withdrawal from Zinjubar district in Abyan to its former deployment areas in Lahj province. “The 9th brigade began the actual withdrawal and all our forces remaining in Abyan will return to their original bases where they were deployed before the clashes of August 2019,” the STC military source said. The pro-government forces that pushed from the northern provinces of Marib and Al Jawf to Abyan also began pulling back towards Shabwa province on the way back to their previous bases. Residents in Al Mahfed district eastern Abyan told<em> The National</em> that pro-government troops were seen on Tuesday evening heading back towards Shabwa. “We saw more than 20 military vehicle carrying dozens of personnel and medium weapons heading from Shuqra district back towards Shabwa, I think these forces are originally the troops which moved from Marib later in August,” a resident said. Earlier on Monday, a tripartite committee of officers representing the STC, the government and the Saudi-led Arab Coalition arrived in Abyan to monitor the troop withdrawal according to the procedures of the Riyadh Agreement. "The tripartite committee held meetings with the commanders of our troops and with the commanders of the troops of the other side, this committee will be responsible to oversee the withdrawal process and ensure that all the troops have pulled back in line with the second stage conditions," the STC military source told <em>The National.</em> “The same tripartite committee is going to monitor the withdrawal process in the province of Shabwa,” the military source said. “The withdrawal process from the province of Abyan will take a whole week starting from Tuesday.” Furthermore, the second stage of the Riyadh Agreement was opened with a prisoner swap between the allies. The government handed over 29 prisoners affiliated with the STC and the southerners handed over 10 prisoners affiliated with the pro-government forces. The prisoners from both sides were first handed to the Coalition which handed them over in Aden on Sunday. Separately, in a meeting with Yemeni President Abdrabu Mansur Hadi in Riyadh on Monday, the special envoy to Yemen Martin Griffiths praised the recent steps by the STC and the Yemeni government to implement the Riyadh agreement and discussed next steps to reach comprehensive peace in Yemen, the international diplomat’s office said. The Saudi-led Arab Coalition supports Yemeni troops and pro-government militias against Houthi rebels who seized the capital, Sanaa, in late 2014 and still control much of northern Yemen. Although allies in the fight against the Houthis, differences between the government and STC sparked clashes between their forces last year. The STC forces seized much of Aden, the temporary capital, before Saudi Arabia intervened to broker a power-sharing agreement signed in November.