Suicide bombings in two mosques that killed at least 126 people in Yemen’s capital of Sanaa on Friday capped off a week of frenzied conflict in a country plagued by the lack of a functioning national government and rising sectarian violence.

Yemen has been marred by political infighting since the ouster of its long-time autocratic president, Ali Abdullah Saleh, in 2012. And so far, an internationally brokered political transition supporting an interim government under Saleh’s vice president, Abed Rabbo Mansour Hadi, has failed to take root.

In September, the country’s powerful Houthi tribal movement took control of Sanaa from its northern stronghold. In February the group dissolved parliament and put Hadi under house arrest. Hadi subsequently fled with his allies to the southern city of Aden, Yemen’s economic hub, where he has tried to continue ruling the country. Hadi’s government remains the most internationally recognized government in Yemen, but its remit has been reduced largely to its new base in Aden.

But even there it is being challenged. That was evident in attacks Thursday and Friday against Hadi — by forces loyal to Saleh — which included multiple aerial attacks on Hadi’s presidential compound and struggle over Aden’s international airport. Saleh, despite being out of power and exiled from the country, has retained influence in the armed forces and thrown his weight behind the Houthis.

The attacks on the two mosques on Friday added another wrinkle to an already complicated and combustible political landscape. The attackers claimed to be part of the Islamic State in Iraq and the Levant (ISIL), which would mark the first assault by the group in Yemen.

"Let the polytheist Houthis know that the soldiers of the Islamic State (ISIL) will not rest and will not stay still until they extirpate them," said a statement by the group claiming to be part of ISIL.

If ISIL’s role were confirmed, it would be a challenge not only to the country’s Houthi movement and its claims to power, but also to Al-Qaeda’s Yemen branch, Al-Qaeda in the Arabian Peninsula, or AQAP.

AQAP is considered Al-Qaeda’s most successful franchise, and it has waged war against the Yemeni state for years, including stepping up its campaign against Houthis, who it views, like ISIL, as infidels because of their Zaydi-Shia brand of Islam.

But AQAP released a statement on Friday saying it was not responsible for the bombings. The group has largely heeded global Al-Qaeda leader Ayman Al-Zawahairi’s call to refrain from directly targeting mosques or intentionally shedding the blood of Muslim civilians.

ISIL seems to hold no such compunction, and it’s embrace of more brutal methods than Al-Qaeda seems to be part of a broader branding war to attract a new generation to its version of radical Islam.

Whether AQAP or ISIL are found responsible for the attacks, sectarian violence seems to be on the rise.

Among those killed on Friday was a leading Houthi cleric, Al-Murtada bin Zayd Al-Muhatwari. Just two days earlier unknown assailants gunned down on of the country’s most prominent journalists and Houthi supporter, Abdel-Karim al-Khewani.

“Yemen does not have a tradition of Sunni-Shia conflict, but AQAP is trying to frame the fight in this context,” wrote International Crisis Group analyst April Longley Alley last month. ISIL would appear to be trying to do the same.

Meanwhile, the continued political paralysis has international organizations and diplomatic missions drawing back their presence in the country.

The United States, United Kingdom and France were among several countries that have in recent weeks closed their embassies in Sanaa. And earlier this month, the World Bank suspended its operations in the country. It cited a “significant decline in the ability of Bank staff to communicate and coordinate with government counterparts.”

For its part, the Obama administration, which previously held up Yemen as a successful example of its counter-terrorism policy in the Middle East, now finds that model imperiled without a reliable ally in Sanaa.

Jamal Benomar, the United Nation’s special adviser in Yemen, on Friday “appealed to all Yemenis to stand united as a broad front against terrorism and the use of violence to achieve political ends.” But the prospect for the necessary constituencies coming together to achieve such a call appears faint for now.

“Individually, each of Yemen’s two overlapping wars — sectarian and political — would be severe enough to cripple the country,” Gregory D. Johnsen, a Yemen expert and journalist with BuzzFeed, wrote on Friday. “Together they might just kill off any lingering hopes of unity.”