The two-decade-long US military presence in Iraq ended on Wednesday with the celebration of “Sovereignty Days”, a national holiday. Some analysts warn that the exit could create a security vacuum, giving Iran a greater chance to influence the country’s domestic conflicts.

Pentagon Spokesperson Sean Parnell said, “This milestone reflects the success of a 12-year campaign that defeated ISIS as an organised military threat in Iraq and across the region.”

“The lesson from the past two decades is ‌that security vacuums can be extremely dangerous,” said Jassim al-Bahadli, an Iraqi analyst who advises the security forces.

This concern stems from the fact that Baghdad requested an exit from the US and for Iranian groups to disarm on Wednesday, but Tehran-backed militias signalled refusal to comply.

US military invaded Iraq in 2003 to capture Saddam Hussein and departed in 2011 after managing the instability and violence that followed.

Washington was legally bound to withdraw by December 31, 2011, as per the 2008 US-Iraq Status of Forces Agreement, but ISIS surged after this withdrawal due to the vacuum.

In 2014, they returned for a 12-year military campaign to assist Baghdad against the Islamic State fighters. The group was then reduced to scattered sleeper cells but still has active fighters.

Kurdish officials are worried about the departure of the US because of the attacks they have faced from Iran and other aligned militias. These attacks, which involved missiles and drones, were intercepted by US military defence systems.

Baghdad’s military has reportedly removed the Erbil-based Patriot and C-RAM defensive systems from Iraq.

The pullout of air defences is particularly concerning because Iraq lacks air defence capability compared to the Iran militia’s weapons.

The timing of the withdrawal is also significant because Washington and Tehran are in an ongoing conflict. Iraq serves as the middle ground between the powers while trying to assert its sovereignty and control without interference.

The withdrawal could play out in two major ways. The US-Iran confrontations would reduce, or the Iran-backed militias would have more freedom to deploy operations, and if its interests are attacked, the US will likely retaliate.