The Pentagon is contemplating means by which it could punish NATO allies who failed to support U.S. operations in the conflict with Iran, internal emails say. 

Among the purported options is expelling Spain from the alliance, according to Reuters, citing an unnamed source. The Pentagon is also reviewing the U.S. position on Britain's claim to the Falkland Islands. Another response to the issue, the email proposes, is suspending "difficult" countries from key positions at NATO. 

However, a NATO official told the BBC that there is no provision in the alliance's founding treaty that would allow for suspension or expulsion of any member. 

The Pentagon note details the frustration the U.S. feels toward allies' reluctance or refusal to allow the U.S. overflight permissions and to use bases. 

President Donald Trump has had harsh words about the lack of support from some allies for not aiding the U.S. Navy in its efforts to open the Strait of Hormuz. He has suggested the U.S. might withdraw from NATO altogether.