Iran fired six missiles at militant strongholds in eastern Syria today, near the area of operations for most of the 2,200 US troops fighting the Islamic State (IS) in the war-torn country. The Islamic Revolutionary Guard Corps (IRGC) said in a statement that the strikes killed several militant leaders accused of plotting last week’s attack on a military parade that killed 25 people.

Why it matters: While US intelligence agencies work to figure out the effectiveness of the strikes, experts tell Al-Monitor that the missile firings show that Iran is focused on increasing the accuracy of short-range weapons that could threaten forward-deployed US and Gulf military forces.

“Their big concern is a US invasion,” said Michael Elleman, a senior fellow at the International Institute for Strategic Studies. “It’s all about raising the costs of action for the United States, the Gulf states or the Israelis against Iran.”

Indeed, Monday’s strikes landed within three miles of American forces, a US defense official told CNN. Iran has bolstered that threat, Elleman said, by adapting short-range missiles with better tail fins and a reshaped nose cone that make the projectiles more accurate. Several drones also accompanied the barrage, indicating that Iran could be using unmanned aircraft to help improve targeting.