求翻译：伊朗上周宣布，在靠近阿富汗东部边境地区的塔巴斯击落一架美军RQ—170哨兵无人侦察机。美方承认丢失一架无人机，但称飞机是因突发故障坠落。是什么意思？

Iran announced last week, in the near Tabas in eastern Afghanistan border area shot down a U.S. reconnaissance unmanned RQ-170 Sentinel. U.S. recognition of loss of a UAV, but said the plane crashed due to unexpected failure.

Iran announced last week, near the eastern border Afghanistan Tabasco RQ downing of a U.S. - 170 sentinel unmanned reconnaissance aircraft. The US acknowledges that lost an unmanned aircraft, but said that this plane is determined by a sudden crash failures.

Iran announced last week, in approaches east Afghanistan the frontier area tower Buss to shoot down a United States military RQ-170 sentry nobody reconnaissance aircraft.The US acknowledged loses an unmanned aerial vehicle, but called because the airplane is arises suddenly the breakdown to crash.

Iran announced last week, near the Afghanistan border areas of Eastern Tower bass the shooting down of a US military RQ-170 Sentinel UAV. The United States side acknowledged that lost an unmanned aircraft, but said planes were due to sudden failure fall.

Iran, shot down an American army RQ-170 sentry's unmanned reconnaissance plane in the tower Bath close to border area of the east of Afghanistan. American side admits losing an unmanned aerial vehicle, but because the trouble happens suddenly to fall to call plane.