Unidentified drones attacked Syrian areas controlled by the Assad regime and Iranian-backed Shi'ite militias at the Hamdan airport near the town of Al-Bukamal in the eastern region of Deir ez-Zor, according to opposition-affiliated TV station Halab Today.Before the attack, three drones were seen flying from the direction of areas under the control of the Syrian Democratic Forces militia, according to Step News, a news agency founded by Syrian activists and journalists. At noon, explosions were heard at the Hamdan airport. Ambulances were sent to the airport, but the number of causalities is unknown.Iranian-backed militias in Al-Bukamal have been targeted by airstrikes multiple times in the past year.Syrian forces and Iranian-backed militias began transferring equipment and materials to Al-Bukamal for the purpose of building bridges across the Euphrates River, according to local news outlet Deir ez-Zor 24.International coalition aircraft intensified flights over the eastern countryside of Deir ez-Zor last week.Sites controlled by Iran in Al-Bukamal have been targeted multiple times by airstrikes in recent months. A strategic border crossing between Iraq and Syria is located in the area.Iranian forces and militias loyal to them are fortifying their positions in the Deir ez-Zor area in eastern Syria where Al-Bukamal is located, according to the Syrian Observatory for Human Rights [SOHR]. In September, at least 37 militants were killed in two airstrikes which also destroyed vehicles, ammunition depots, weapons and buildings in the Al-Bukamal area. Many of those killed were of Iraqi nationality.The attacks in the Al-Bukamal area have been blamed on both Israel and Saudi Arabia."Saudi fighter jets have been spotted along with other fighter jets that have attacked facilities and positions belonging to Iranian militias," said an unnamed source to the Independent in Arabic. The attacks targeted positions belonging to the Quds force of the Iranian Revolutionary Guard Corps in Al-Bukamal and other areas near the Iraq-Syria border.Saudi sources later denied the report, according to the Independent.On September 9, airstrikes allegedly carried out by Israel destroyed a military base in the area under Iranian control, according to the SOHR.Seth J. Frantzman contributed to this report.