British intelligence reportedly alerted the U.S. to Trump-Russia ties back in 2015

President Trump. — (Image credit: Drew Angerer/Getty Images)

British spy agency GCHQ shared intelligence information with the U.S. that first alerted the Americans to the potentially troublesome ties between then-candidate Donald Trump's campaign team and Russian operatives, The Guardian reports. GCHQ alerted U.S. agents to suspicious "interactions" between Trump-orbit individuals and known or suspected Russian agents in late 2015, and alongside other European intelligence agencies informed the U.S. of the connections.

GCHQ was not conducting a targeted operation against Trump, but rather the alleged conversations were "picked up by chance," The Guardian notes. But apparently U.S. agents had to be shaken alert by their counterparts abroad:

[T]he FBI and the CIA were slow to appreciate the extensive nature of contacts between Trump's team and Moscow ahead of the US election. This was in part due to US law that prohibits US agencies from examining the private communications of American citizens without warrants. "They are trained not to do this," the source stressed. "It looks like the [US] agencies were asleep." [The Guardian]

Since July 2016, the FBI has been investigating whether Russia meddled in last year's election, and whether anyone involved in the Trump campaign may have aided their efforts if so. Read more about how British intelligence broke the story at The Guardian.