Recent changes in the dynamics of Yemen’s civil conflict — widely seen as a proxy war between rivals Saudi Arabia and Iran — are making it very hard to predict what could happen next in the Middle East.

Tensions between Saudi Arabia and Iran ramped up Tuesday following another missile launch from Houthi rebels in Yemen aimed at the Kingdom. Saudi Arabia said the blame for the missile, reportedly intercepted on its way to Riyadh, lay directly with Iran.

“This hostile and indiscriminate act by the Iran-back Houthi armed group proves the continued involvement of the Iranian regime in supporting (the) Houthi armed group with qualitative capabilities,” a Saudi spokesman said Tuesday, according to the country’s press agency. Iran has denied the allegations.

An expert in Middle East affairs told CNBC it was worrying as it was difficult to predict where Saudi Arabia and Iran’s rivalry could lead.

“We don’t know where it’s going and we can’t really talk about it like an established dynamic with established norms. This is a totally new situation for the region and I really struggle to predict what’s going to happen next,” Marcus Chenevix, Middle East and North Africa (MENA) analyst at TS Lombard, said Wednesday.

“The thing to remember with Saudi Arabia and Iran is that this is very new. People act like Sunni and Shia (rivalry) is ancient but it’s not actually. What’s going on is that this is the first time for a very long time that there hasn’t been an external arbiter in the Middle East who basically defines everyone’s diplomatic relationships,” he said.

“For a long time it was America and Russia, then it was just America and now there’s no one. So there’s a power vacuum and that power vacuum is pretty recent — the Iranians saw it first and Saudi Arabia has only really been engaging in this kind of rivalry for the last five years.”

The missile launch on Tuesday came as Yemen’s civil war drags on. Saudi Arabia and Iran have taken opposing stands in an ongoing battle for power and dominance in the country that followed the “Yemeni Revolution” in 2011 which prompted regime change.

Sunni-dominated Saudi Arabia and the Western world back Yemeni President Abdrabbuh Mansour Hadi, who became head of state after an uprising against former President Ali Abdullah Saleh in 2011.

Meanwhile, the Houthi movement wanted Saleh back in power and, allegedly with Iranian support (which Tehran denies), took control of Yemeni capital Sana’a and government ministries, pushing the Hadi government into exile.

The alliance between the Houthis and Saleh ended abruptly in November when the former president decided to end the allegiance. He was then killed by the Houthi group while trying to flee the capital.

That now leaves a delicate situation in which Saudi-backed forces in Yemen are fighting allegedly Iranian-backed Houthis.

TS Lombard’s Chenevix said that Saleh’s death was a game changer in the conflict.

“The really big development is not the missile but the death last month of Ali Abdullah Saleh, the former Yemeni dictator. In the past the Yemen civil war was about Yemen, it was about the north of Yemen not wanting to be federalized and cut off from oil,” he said.

“But now that Saleh is dead and it’s just the Houthis versus the Saudi-supported cause, the Yemen war has become a lot more of a proxy war between Saudi Arabia and Iran — and that makes it much more troublesome, and it makes it a lot more about Saudi. I would expect to see a lot more missiles coming out of Yemen,” he said.

While the U.S. called Tuesday for Iran to be punished for its support of the Houthi rebels (among other things), there is opposition in the United Nations Security Council (notably from Russia) over whether to do so.

Meanwhile, the civil war in Yemen shows no signs of abating, with Saudi Arabia continuing to lead airstrikes against Houthi rebels in the capital. According to the United Nations, Saudi coalition airstrikes have killed 136 non-combatants in Yemen since December 6.

The war is widely seen as a proxy conflict between Sunni-dominated Saudi Arabia and its regional nemesis, the Shia-dominated Iran. Saudi Arabia blames Iran for supplying the Houthis with weapons, which Tehran denies.

Chevenix said the war was “devastating” for Yemen and its civilians.

“The effect on Yemen has been devastating. Yemenis talk to say it’s like Somalia. The Yemen Data Center reckons there’s been about 16,000 airstrikes, a lot of which were on civilian targets, so the effect is absolutely devastating.”