The US has blamed a "foreign actor" for the RAF Fairford incident and warned there is "a lot more news" that will come to light following the alleged terror plot.
Secretary of State Marco Rubio spoke to Fox News on Monday night and said "there will be repercussions".
Five men, all from London and in their 20s, were arrested on suspicion of terrorism and explosives offences after three suspicious vans were found near the Gloucestershire base used by US forces.
Rubio declines to name actor
The US Secretary of State did not name the "foreign actor" he believes was behind the incident during the interview, saying: "I won't get into great detail about that yet."
Rubio said: "I know a lot of people are disturbed by the news that some of these people have been released on bail... Obviously we're engaging with them on all of that."
"But suffice it to say that beyond that, I would argue that they've been very cooperative and very helpful on something that's very serious incident, and I think it ties us to the reality here."
Repercussions warning
The senior Trump administration official said the US was "dealing with elements in the world", adding: "In the case of Iran, for example, who have openly threatened to attack American interests globally, we're going to always take that very seriously."
"There will be repercussions for that if it ever were to happen or even attempted, but what happened this week, it could have been and was, I think, a very serious threat. And I want to thank the UK for their cooperation and their help on it."
He added there will be "a lot more news that will come out" about the incident in the coming days however "there's only so much I can say right now at this point about it, other than this is a very serious thing".
