I found the following news report on Reuters/Yahoo!:

Khamenei vows no retreat on Iran election result. The unexpected upheaval in Iran has thrown a spanner into Obama’s plans to engage the Islamic Republic in a substantive dialogue over its nuclear program, which Tehran says is peaceful but which the West suspects is for bomb-making.

Although the article is in English, I am pretty sure that these reporters are not American because we do not use the idiom “throw a spanner.” In America, we call spanners wrenches. So, in American English, we would say that the “upheaval in Iran has thrown a [wrench] into Obama’s plan.”