一名美国高层官员说，俄罗斯战机空袭了在叙利亚南部与伊斯兰国作战的反政府武装，其中包括受到美国支持的战斗人员。
这位要求不透露姓名的官员说，俄罗斯战机最近一段时间很少在该地区发动空袭，最新事态引起人们对俄罗斯意图的“严重关注”。空袭地点位于叙利亚跟伊拉克和约旦边界附近。
这位官员周四表示，美国将要求俄罗斯对这一举动做出解释，并保证不再发动空袭。
美国一直对俄罗斯进入叙利亚持批评态度，并屡次拒绝与俄罗斯军队在叙利亚境内协同行动，美国指责俄罗斯军队帮助叙利亚总统阿萨德巩固政权。
星期四的空袭很可能会让本已处于紧张状态的美俄关系受到考验。一天前，美国国务卿克里警告俄罗斯和叙利亚必须遵守今年早些时候签署的停火协议。
克里星期三会晤伊朗官员后说，俄罗斯必须知道，美国的耐心不是没有限度的。
Russian aircraft have dropped bombs on rebels battling Islamic State in southern Syria, including those supported by the United States, a senior U.S. official said.
The official, who asked not to be identified, said Russian jets had not been active in the location along the Syrian border with Iraq and Jordan, for some time, which raised “serious concerns” about the intentions of the Russians.
“We will seek an explanation from Russia on why it took this action and assurances this will not happen again," the official said Thursday.
In the past, the U.S. has been critical of the Russian presence in Syria, and has repeatedly refused to work with Russian forces in the country, which the U.S. accused of working with Syrian President Bashar al-Assad to consolidate his power.
The bombing Thursday is likely to test already strained relations between the U.S. and Russia, and came just a day after U.S. Secretary of State John Kerry warned Russia and Syria to respect a cease-fire treaty signed between the three nations earlier this year.
"Russia needs to understand that our patience is not infinite." Kerry said Wednesday following a meeting with Iranian officials.
