TEHRAN, Iran (AP) — Iran's powerful Revolutionary Guard has begun a military exercise in the northwestern Kurdish region near the Iraqi border ahead of a Kurdish independence referendum in the neighboring country.

The Guard's website did not say how long the drill will last, only that airborne and missile units will participate in the exercise.

Iraq's Kurds are set to vote Monday in a referendum on support for independence. The Kurds are likely to approve the referendum, but the non-binding vote is not expected to result in any formal declaration of independence.

Iran and Iraq have been close allies since the 2003 U.S.-led invasion of Iraq toppled dictator Saddam Hussein. Both are opposed to Kurdish independence, and Baghdad has said the referendum is unconstitutional.