Start date: 2003
Total length: Uncertain
Official purpose: Prevention of weapons smuggling and terrorist infiltration

The border between Saudi Arabia and Yemen has long been a source of political dispute, particularly from 1990 — when North Yemen and South Yemen became unified — to 2000, when the two countries signed an agreement. Fighting broke out between border guards in 1994 and again in 1998, when three Yemeni soldiers were killed. The 2000 border treaty eased tensions between the governments, but did not eliminate controversy; Saudi Arabia has decried, and attempted to stanch, the illegal flow of weapons and other goods across the border.

The Saudis have long asserted that a secure border is essential to their efforts to maintain law and order. This claim is not entirely without merit: in a 12-month period from 2002 to 2003, more than 30 Saudi border guards were killed in the border town of Jizan, Saudi Arabia. In May 2003, terrorist attacks in Saudi Arabia attributed to Al Qaeda killed more than 50 people, and the Saudi government vowed to crack down on terrorist infiltration. Yet Yemen has argued that Saudi Arabia has overreached by accusing Yemeni smugglers of fomenting terrorism; after all, homegrown Saudi terrorists — with or without weapons obtained from across the border — cannot be blamed on Yemen.

In 2003, Saudi Arabia began construction of a concrete pipeline that served as a border barrier. Yemen protested, citing the 2000 border agreement. After meetings between the two governments, in 2004 Saudi Arabia announced that it was halting construction and that future building along the border would adhere to the 2000 treaty with Yemen. The future of the barrier remains unclear.