An unidentified attackers in eastern Afghanistan fired rockets at a U.S. base Saturday, the latest in a series of attacks against American forces. Three rockets were fired at the U.S. base in Asadabad, the capital of Kunar province, U.S. military spokesman Col. Rodney Davis said. The rockets missed, as scores of others have over the past year, and they caused no damage or casualties. "We've seen an increase in the number of engagements and rocket attacks ... over the last few months, but we believe that there is something seasonal to that," Davis said. Insurgents appear to be increasingly launching attacks now that freezing temperatures have given way to warmer weather, Davis said. Last week, insurgents fired on patrolling U.S. forces near Shkin, a volatile town in Paktika province near the Pakistan border, triggering a firefight that left four attackers dead. Two Americans died in late April after a battle with at least 20 rebels in Shkin, and in late March two U.S. troops died when their convoy was ambushed in the southern province of Helmand. Aid workers and Afghan military forces nominally loyal to the government have also come under increased attack in southern and eastern Afghanistan in recent months. On June 7, a suicide bomber struck in the capital, killing four German peacekeepers and one Afghan civilian. The insurgents are a mix of holdouts from the former Taliban regime, fugitive members of the Al-Qaida network and loyalists of Qalbuddin Hekmatyar, a former prime minister. About 11,500 coalition troops, most of them Americans, are headquartered at Bagram Air Base, north of the capital. In the north and east, they routinely conduct patrols and operations in search of rebels and weapons caches. **PHOTO CAPTION*** An American soldier takes picture of his colleague with two soldiers of the 3rd Afghan National Army Mechanised Battalion during their graduation ceremony at a military base in Kabul, Afghanistan (news - web sites), Thursday, June 12, 2003. About 540 Afghan soldiers including officers and soldiers were graduated. (AP Photo/Rafiq Maqbool)