The number of U.S. troops in Iraq has fallen below 50,000 — the lowest level since the U.S-led invasion in 2003, the military said Tuesday.

The drop comes ahead of President Barack Obama’s deadline to bring down troop levels by August 31.

The military said U.S. troops will now transition to Operation New Dawn, effective September 1. In this phase, the United States will help train Iraqi security forces until the end of its mission in December 2011.

On Monday, Vice President Joe Biden said that the overall level of violence in Iraq has now declined to the point that some early U.S. veterans of the conflict “would not recognize” the country today.

The roughly 650,000-member Iraq security force is “already leading the way to defend and protect [the] country,” he said.

(Read More: CNN)