The top U.S. military officer says it's too early to talk about a full American troop withdrawal from Afghanistan, as peace talks with the Taliban appear to be near a final agreement.

Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, says any peace agreement will be based on security conditions on the ground. He says Afghan forces aren't yet able to secure the country without help from allied forces and it's not yet clear when they'll be.

Defense Secretary Mark Esper says the U.S. will keep all options on the table.

Afghanistan's government expects that U.S. envoy Zalmay Khalilzad will soon update officials in Kabul on talks with the Taliban. A Taliban spokesman says they're close to a final agreement to end the nearly 18-year war.