MOSCOW -- Russia is reasserting its role in Central Asia with a Kremlin push to eject the U.S. from a vital air base and a Moscow-led pact to form an international military force to rival NATO -- two moves that potentially complicate the new U.S. war strategy in Afghanistan.

On Wednesday, Russia announced a financial rescue fund for a group of ex-Soviet allies and won their agreement to form a military rapid reaction force in the region that it said would match North Atlantic Treaty Organization standards. That came a day...