WASHINGTON—President Barack Obama has nominated Marine Gen. John Allen, the top U.S. commander in Afghanistan, to be the next NATO supreme allied commander. Allen is slated to replace Admiral Jim Stavridis (stav-REE'-dihs) in the spring, and Marine Gen. Joseph Dunford, the assistant Marine commandant, would take the top Afghanistan job. The changes must be confirmed by the Senate.

Obama said in a statement that Allen served with distinction as U.S. commander in Afghanistan, helping the country through a critical period as the U.S. prepares to withdraw its troops, starting in mid-2013.

Allen is expected to provide recommendations by the end of the year on the pace and number of U.S. troops leaving Afghanistan. Dunford has been assistant commandant since October 2010. Allen took over the Afghanistan job in July 2011.