The former National Highway 21 (NH 21, now numbered NH 3), the road through the Kullu Valley, terminates at Manali. The road northwards over the Rohtang Pass to Keylong in Lahaul and Spiti district and on to Leh in Ladakh is not a national highway. Nonetheless, the Leh-Manali Highway has become very busy during the summer months as an alternate military route since the Kargil Conflict in 1999. Traffic jams are common as military vehicles, trucks, and goods carriers try to navigate the tight roads and rough terrain, compounded by snow and ice at certain points and the large number of tourist vehicles.