Iran’s top security chief has defended the country’s involvement in Syria, calling it essential for national security.

“We have no regrets about the costs incurred in Syria because our presence and expenses were for our own security,” said Ali Akbar Ahmadian, secretary of Iran’s Supreme National Security Council, in an interview with the website of Ali Khamenei’s office.

“The Islamic Republic was never meant to fight in place of the Syrian army,” he added.

Iran is estimated to have spent between $30 billion and $50 billion over the past decade to support the now-ousted Bashar al-Assad government, including deploying troops, supplying weapons, and providing financial aid.