A major Sudanese naval base was targeted by armed drones, the fourth such raid on the Red Sea coast in as many days, as authorities struggle to tame a blaze at a nearby port that’s crucial to the flow of humanitarian aid.

The Wednesday attacks — the latest salvo in a two-year war between Sudan’s army and the Rapid Support Forces militia — targeted the Flamingo Bay naval base, according to two port officials at the scene of the attack. The extent of the damage was unclear.

Ships docked at Port Sudan’s southern terminal have been removed from their berths for safety, the officials said, while emergency workers battle to contain a fire that broke out when fuel-storage facilities were hit by drones on Tuesday. That forced the terminus to shut down, halting operations at Sudan’s main conduit for trade and humanitarian assistance.

ALSO READ: Drone strikes target strategic sites in Port Sudan

“Every destruction of civil or military structures will only increase the people’s strength and cohesion,” Abdel Fattah al-Burhan, the head of the Sudanese army, said in a speech in front of a billowing smoke cloud coming from the port. “We say to those who attack Sudan: the hour of retribution will come.”

The assaults on Port Sudan represent a new phase in fighting that’s left as many as 150,000 people dead since April 2023 and sparked the world’s largest humanitarian crisis. While much of Sudan’s capital, Khartoum, has been leveled by air strikes and street-to-street fighting, the Red Sea city had been spared and was a haven for Sudanese fleeing violence elsewhere.

A series of RSF aerial attacks have targeted major infrastructure that’s crucial to the military’s war efforts since Sunday, temporarily canceling flights and throwing Port Sudan into chaos.

READ MORE: Paramilitary attacks kill at least 300 in SW Sudan in 2 days, says govt

The coastal city is critical for transporting trade to landlocked nations in central Africa, and sits near facilities that export crude from neighboring South Sudan to mainly Asian markets. It’s also an essential cog for aid agencies to deliver food and medicine to millions of people suffering from malnutrition.

The RSF said in a statement on Tuesday that “Islamist terrorist groups in Sudan and the Red Sea” are using “civilian infrastructure and state institutions to continue a war they have no intention of ending peacefully.” The group hasn’t claimed direct responsibility for the attacks.