Saudi Arabia's King Salman
Saudi Arabia's King SalmanReuters

As the Shi'ite Houthi militia backed by Iran continues to solidify its hold in Yemen, and Iran seems likely to get a favorable deal in nuclear talks ahead of a March 31 deadline, US officials revealed Tuesday that Saudi Arabia has started deploying heavy military equipment on its border with Yemen.

The Houthis have begun pushing south after conquering the capital city of Sana'a last September and overthrowing the government, replacing it with their own temporary government. Over the weekend they took control of the central city Taiz, moving ever south, reports Reuters.

Regional tensions between Iran and Saudi Arabia are being played out in Yemen, with Iran backing the Houthis and the Saudis supporting US-backed President Abd-Rabbu Mansour Hadi.

Two US government sources speaking to Reuters detailed that the armor and artillery being moved to the border by the Saudis could either be used offensively or defensively, although two other officials said the deployment appeared defensive in nature.

One source from the US government called the new buildup on the border "significant," saying the Saudis may be readying to launch airstrikes on the Houthis if they attack Hadi in his refuge of the southern seaport Aden, a key strategic point controlling the entrance to the Red Sea and ultimately Eilat. Hadi fled Sana'a for Aden in February, escaping from the Houthis.

"The Saudis are just really deeply concerned about what they see as an Iranian stronghold in a failed state along their border,” US Ambassador to Yemen Matthew Tueller told Reuters on Monday. The Saudi-Yemen border is 1,800 kilometers (1,100 miles) long.

If the Houthis manage to break through towards Aden, a former senior US official told the paper on condition of anonymity that the chances of the Saudis successfully repelling them are slim, and that Hadi is "pretty well pinned down."

Saudi Arabia on Saturday hosted talks with Gulf Arab neighbors backing Hadi, offering "all efforts" to stabilize Yemen, which has seen clashes between the Houthis on one side and Al-Qaeda and Sunni militias on the other.

And on Tuesday Yemen asked the UN Security Council to support military action by "willing countries" to fight the Houthis and check their power grab. For its part, the US evacuated all its remaining personnel from Yemen on Saturday, including around 100 specials ops forces.

The Saudis have been on edge as Iran is seen as moving closer to having its nuclear program given a free pass by a weak nuclear deal with world powers, a move that experts predict would lead Saudi Arabia to preempt the Islamic regime by arming itself with nuclear weapons as part of a regional nuclear arms race.