The rebel Free Syrian Army on Tuesday accused President Bashar al-Assad of moving chemical weapons to Syria’s border, according to Agence France Presse.

In a statement, the FSA said, “According to our information, the regime began moving its stocks of weapons of mass destruction several months ago… with the goal of putting pressure on the region and the international community,” according to AFP.

On Monday, foreign ministry spokesman Jihad Makdissi confirmed that Syria did possess chemical weapons but would only use them against foreign attackers, not against its own civilians.

President Barack Obama responded to the news, saying, “They will be held accountable by the international community and the United States should they make the tragic mistake of using those weapons,” according to AFP.

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Assad also appointed a new security chief and senior intelligence officials on Tuesday, following the bomb attack last week which killed four members of his inner circle, according to the Associated Press.

Maj. Gen. Ali Mamlouk was appointed as the head of the National Security Council, and Maj. Gen. Abdel Fattah Qudsiyeh was named the council’s deputy chief, said the AP, citing an official.

Longtime Assad aide Maj. Gen. Rostom Ghazali was named the head of the Political Security Department and Maj. Gen. Deeb Zeitoun will head General Intelligence. Maj. Gen. Rafiq Shehadeh was appointed the new head of Military Intelligence, according to the official.

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The appointments come as rebels have launched a major military campaign in Damascus and Aleppo, Syria’s largest city. According to the BBC, fighter jets bombed eastern parts of Aleppo on Tuesday, a significant escalation in the conflict.

Rebels launched the offensive over the weekend and fierce fighting was reported close to Aleppo’s Old City. Government troops launched shells and rocket fire as their forces attempted to wrest back control. According to the pro-opposition Local Co-ordination Committees, at least 80 people were killed on Tuesday, including 20 in Aleppo.