US Secretary of State Marco Rubio has arrived in Reykjavik, Iceland, for the first leg of a four-day European tour in which he will also visit Greece and Portugal.

“Economic and security collaboration” top the agenda for his talks on Monday with Icelandic officials, according to a statement from the Department of State.

Ahead of his departure, he told reporters he would not directly tie the United States’ decision to remove its B-1 bombers from the British base of Fairford to last week’s incident.

“I wouldn’t just directly tie that to the move that was made,” Rubio told reporters, adding that “the Department of War is constantly reallocating resources where they need to be”.

Rubio asserted confidence in the security of all US bases and praised United Kingdom authorities’ cooperation.

Five British men were arrested near the British airbase at Fairford on suspicion of preparing “terrorist acts”, and were later released on bail. A sixth man, a dual UK-Iranian national arrested separately in London, has also been released on bail.

B-1 bombers were returned to the US. They had been used for strikes on Iran.

A NATO military source had, however, said: “It is still believed that Iran poses an acute threat to US assets in the UK”.

Iran’s Revolutionary Guards previously said the Fairford base was a legitimate target, but Tehran denied any links to last week’s incident.

Rubio is also visiting Greece to lead the US delegation for the sixth US-Greece Strategic Dialogue, focusing on defence cooperation and regional and energy security, and will wrap up his tour in Lisbon, where he will discuss defence, economic and technology cooperation.