Syria is weighing military assistance to key ally Saudi Arabia, U.S. and Syrian officials said, as the Iran-aligned Houthis step up missile and drone attacks on the kingdom that killed three people at Saudi airports this week.

The possible entry of Syrian forces into the battle, a spillover of the ⁠US-Iran conflict, shows how Yemen's reignited civil war has added ⁠new chaos to a region already aflame and risks drawing regional states into grueling mountain fighting.

Saudi Arabia has pushed for support from allied nations, including Türkiye and Pakistan, even if only in a logistical or purely defensive capacity, an effort made more ​urgent by the Houthi strikes on its infrastructure such as this week's deadly airport attacks.

A succession of ​loud ⁠booms were reported in Riyadh Thursday morning. There was no immediate official comment and no public early warning alerts, although some diplomats said they had received warnings, and some schools in Riyadh warned parents of shelter in place orders, according to Reuters.

Yemen's Houthi rebels, however, claimed Thursday that it had attacked King Khalid International Airport in Riyadh with a ballistic missile. The Saudi government media office did not immediately respond to a request for comment.

One person had been killed in a strike on Riyadh airport and two others in an attack on Abha airport in the southwest Tuesday and Wednesday, Saudi Arabia said late Wednesday.

Purely defensive

Meanwhile, the U.S. and Syrian officials said Damascus was carefully considering military support, including the option of defensive aid to protect Saudi Arabia from attacks or deployment in an offensive capacity to help Saudi-backed Yemeni troops take the fight to the Houthis.

Yemen's long-running civil war, which paused with a cease-fire in 2022, ⁠has ⁠erupted again in recent weeks with the Houthis seizing stretches of the Red Sea coast last month, including along the vital Bab el-Mandeb Strait.

The Houthis have said they were responding to attacks from the Saudi-backed government, which the government denies.

The group's threats to shipping along a waterway that has become ever more critical for Gulf oil exports since Iran's attacks in the Strait of Hormuz and its targeting of Saudi cities and infrastructure, have drawn the kingdom back in.

In response to a request for comment to the Syrian Foreign Ministry, a Syrian diplomat said Syria stood firmly with Saudi Arabia in the face of Houthi attacks but that the government's primary focus was on domestic priorities such as recovery from the country's 14-year civil war.

"Should Saudi Arabia request any military cooperation or exchange of expertise, this would take ⁠place exclusively through official channels and within the framework of the bilateral agreements governing relations between our two brotherly countries," the diplomat said in a statement.

Riyadh seeking support

This week, Saudi-backed forces launched a counterattack, taking back areas around the strait as they push to reverse the Houthis' gains of last month.

However, in a ​messy war with several frontlines, the Houthis have also made some gains of their own this week, surrounding the country's third-largest city of Taiz ​by taking territory along its main mountain road to Aden.

The fighting, which pits the Houthis against a coalition of Saudi-backed forces under the internationally recognized government, has led to a humanitarian crisis in the poorest Arab state, displacing 200,000 people since the conflict resumed.

Saudi ⁠Arabia this summer ‌agreed the Mecca ‌pact with Türkiye and Pakistan, committing all three countries to come to each other's defense, though Ankara ⁠still needs to ratify the treaty internally.

NATO-member Türkiye said Wednesday it was sending ‌mainly defensive and technical support to the kingdom to help in the fight against the Houthis, and a Turkish official said this was expected to take the form of military equipment, ​intelligence sharing and weapons systems.

Pakistan, meanwhile, has flown cargo planes of ⁠military equipment to Aden in southern ​Yemen to help in the battle against the Houthis, sources in Pakistan have said and has deployed troops inside Saudi Arabia to help defend the kingdom's borders.