U.S. Secretary of State Marco Rubio told Fox News last night that the weekend incident in which five men were arrested outside RAF Fairford in Gloucestershire, England, “clearly” involved a foreign power. “What could have happened in the UK over the weekend is a very serious situation,” Rubio said, reported the Guardian. He added that it “clearly involves the hands of a foreign actor.” The Guardian notes, however, that he provided no evidence for his claims.

Rubio made his comments after British police released the five suspects on bail, making it appear that British police officials don’t believe that the five men were about to carry out a terrorist attack on the base. Police said all five were from London, one aged 23, three aged 24, and one aged 25, according to an earlier report. The head of UK counter-terrorism policing, assistant commissioner Laurence Taylor, said that the release of the men on bail did not mean the investigation was over and that they were subject to “stringent conditions.”

Trump claimed on Sunday that the men “were looking to do big damage” at the base, used by the U.S. Air Force, which was taken as revealing a serious terror plot. On Monday, he expressed surprise that the suspects had been let out on bail. “I would not have released them,” Trump said.