The United Arab Emirates have stepped up their involvement in the war in Yemen as Saudi Arabia backed Islamists the smaller Gulf state still regards as a threat.

Earlier this month, the Emirates sent some 3,000 troops to Yemen. The Financial Times reports that their involvement was critical in pushing the Houthis out of Aden, formerly the capital of South Yemen, where resistance against the Shia rebel group from the north is concentrated.

The Emirates also deployed armored vehicles and tanks while some one hundred special forces have been on the ground since May.

Five Emirati soldiers were recently killed in fighting, according to state media.

Although the rich Gulf states seldom get involved militarily in regional conflicts, preferring dollar diplomacy and support for proxies over risking their own soldiers, the Emirates have invested heavily in the past decade to bolster their armed forces.

According to the Financial Times, the Yemen operation demonstrates “the Gulf state’s increasing willingness to flex its military muscle to pursue regional political objectives that include curbing the rise of Islamist extremism in Libya and Syria and checking perceived Iranian encroachment in its backyard.”

The federation, which is governed from Abu Dhabi, sent fighter jets to Egypt last year to strike Islamists in Libya. Like its neighbors, it has also supported the uprising against Syrian president Bashar al-Assad, an Iranian ally.

Although Saudi Arabia and the Emirates both consider the Yemeni Houthis proxies for their regional nemesis Iran and claim to seek the restoration of President Abd Rabbuh Mansur al-Hadi — whom the Houthis forced to flee the capital, Sana’a, in February — the former is less discriminate about which anti-Houthi groups to back.

With Hadi lacking a support base of his own and southern separatists — who make up the bulk of the anti-Houthi alliance — unlikely to venture north to retake the capital, the Saudis have had to make common cause with Yemen’s Muslim Brotherhood, Islah, to defeat the rebels.

In 2012, fearful that Islah would hijack another “Arab Spring” uprising in the Middle East, Saudi Arabia intervened and replaced Yemen’s longtime ruler, Ali Abdullah Saleh, with Hadi.

Saleh, a northerner who presided over Yemen’s unification in 1990, teamed up with the Houthis to bring down his successor.

Peter Salisbury argues at World Politics Review that the Emirates are more apprehensive about the possibility of an Islah takeover in Yemen. They have cracked down on Islamists organizations at home, including a group also known as Islah that the government said had ties to the Muslim Brotherhood.

With boots on the ground, could the UAE push for a government in Sana’a more to its own liking or would it defer to Riyadh, which under King Salman has changed tack and come to embrace the political Islamists it once declared terrorists, much to the chagrin of Abu Dhabi and Cairo?

If Saudi Arabia, which leads the multinational Arab military intervention in Yemen, pushes Islah and other allies north, perhaps coordinated with an offensive of its from own across the border, it “would likely mean an even more destructive phase to a war that has already cost thousands of lives and precipitated a humanitarian disaster,” according to Salisbury.

It would also mean that the Emirati forces backstopping anti-Houthi fighters in southern Yemen might be called on to take part in the war in the north, costing more lives and dragging the UAE deeper into Yemen’s conflict. And if the war were won, the Emirati troops might not be able to withdraw overnight; they could well be forced into a lengthy stay in Yemen to maintain any fragile peace.