Egypt is alluding to the possibility of renewed tensions with Ethiopia over the lack of progress in the latest round of negotiations dealing with the Grand Ethiopian Renaissance Dam last week.

The dam, in Ethiopia’s stretch of the Nile, has been controversial with Egyptians, who see it as lowering the water level of the river as it traverses through Egypt.

The dispute has already led to cyber warfare. Last June, according to Foreign Policymagazine, an Egyptian hacker group hacked more than a dozen Ethiopian government sites. They replaced the content of each page with an image of a skeleton pharaoh holding a scythe and a scimitar. “If the river’s level drops, let all the Pharaoh’s soldiers hurry,” a warning message said. “Prepare the Ethiopian people for the wrath of the Pharaoh.”

The negotiations fell apart during the same time as Cairo sent its Air Force to North Sudan for joint combat exercises. The exercise was not aimed at a specific country, Sudan said.

However, Egypt was less diplomatic.

“I tell our Ethiopian brothers: ‘We should not reach the level that you mess with a water drop in Egypt, because all options are open,’” Egyptian President Abdel Fattah al-Sisi said on April 7 after the negotiations fell apart. “Cooperation between each other and building together is much better than when we disagree and struggle.”

With negotiations not producing any results, Ethiopia is promising to follow through on its goal of filling the dam’s reservoir for a second time before the summer.

Egypt, for its part, blamed Ethiopia for refusing a Sudanese request to bring in a foreign mediator.

Both countries have demanded that Ethiopia agree to an agreement to limit the dam’s impact. So far, Ethiopian President Abiy Ahmed has refused.