Saudi Arabia is building a 1,800 km border fence to bolster security at its frontier with Yemen.
Once completed, the fence will run from the Red Sea coast to the borders with Oman and is meant to secure the troubled area between the two countries.
It consists of a network of sandbags and pipelines, three meters high, filled with concrete and fitted with electronic detection systems.
Yemen is considered as a base of al-Qaeda in the Arabian Peninsula (AQAP), and therefore Saudi Arabia is keen to secure its borders against possible infiltrations and attacks.
Border security has worsened following the Yemeni revolution in 2012 with thousands of illegal immigrants, gun runners and smugglers trying to slip from poverty-stricken Yemen into Saudi Arabia.
The kingdom is making a concerted effort to clamp down on illegal immigrants entering the country for reasons of work.
Saudi King Abdullah on Saturday ordered a three-month delay to a crackdown against illegal immigrants which has already led to thousands of deportations in order to give foreigners in the kingdom a chance to sort out their papers.
On Monday, Yemen expressed concern at the rapid pace of deportations of its workers, who provide around $2 billion in remittances a year to Saudi Arabia’s impoverished neighbor.
Trouble on the southern front
The first section of the fence has already been built along the coast, stemming - but not stopping - the tide of illegal immigrants.
Militias and smugglers have already begun to show ingenuity in their bid to circumvent the new fence, using mules, women and secret routes to enter Saudi Arabia.
In an interview with BBC News said Saudi border official Lt Col Hamed al-Ahmari said five Saudi border guards were recently killed in shoot-outs with well-armed smugglers along the border.
Saudi Arabia began the construction of the border fence in 2003, then halted construction operations in 2004 after protests from the Yemeni government. Yemen cited the 2000 border treaty between the two countries in which the delineation of the dividing line was decided.