Yesterday’s marathon hearing at the House Intelligence Committee in the US Congress had all the makings of an American TV courtroom drama.

For five gruelling hours, the committee measuredly and methodically cross-examined FBI director James Comey and the head of the National Security Agency Admiral Michael Rogers about Russian involvement in the 2016 US presidential campaign.

But even before the hearing started, US president Donald Trump sought to control the narrative, tweeting in the early hours that the Democrats “made up and pushed the Russian story as an excuse for running a terrible campaign” and continuing: “The real story that Congress, the FBI and others should be looking into is the leaking of classified information. Must find leaker now!”

This argument was picked up in the hearing by Republicans who relentlessly focused on alleged leaks by the intelligence services and questioned Comey about the protections in place to ensure US citizens who are subject to surveillance are not unfairly “unmasked”.

What happened in effect yesterday was that two conversations took place in Room 1100 of the Capitol’s Longworth Building – one by Republicans about the leaking of intelligence information to the press, the second about the matter on the agenda – Russian interference in last year’s presidential election.

Classified leaks

Which narrative takes hold and lodges in the public imagination arising from Comey’s testimony remains to be seen.

With Trump due to attend an event in Kentucky last night officially described by the White House as a “Make America Great Again” rally, the US president was expected to fight back against Comey’s confirmation of an inquiry into links between Trump’s campaign and Russia and to focus on the “leakers”.

On the substantive issue of Russian involvement in US elections, Comey’s testimony was hugely significant in a number of ways.

In an unusual move an FBI director confirmed that an investigation into the Trump campaign’s links with Russia - and not just an investigation into Russia interference in the 2016 presidential campaign - was under way.

He also dismissed claims by Trump that president Obama ordered the wiretapping of his phone – an allegation that has become more and more problematic for Trump over the last week as the president and his advisers have sought to backtrack from the allegations made in his original tweet on March 4th accusing Obama of interference.

Significantly, Comey also disclosed that the investigation into the Trump campaign began last July – just as the FBI closed its initial investigation into Hillary Clinton’s use of a private email server while secretary of state, and before Comey controversially announced he was investigating fresh emails connected with Clinton in the final days of the election campaign.

Similarly, NSA chief Michael Rogers refuted claims that the Obama administration asked British intelligence services to spy on Trump, asserting that such a move would be in breach of an agreement between the two countries for decades.

Where the investigation will lead is unclear.

Comey declined to give any timeline on when the inquiry will conclude but his suggestion that there is now a criminal investigation into Russian interference in the campaign is potentially explosive for Trump.

Meanwhile, US authorities are planning to ban passengers travelling on certain US-bound foreign airline flights from carrying into the cabin larger electronic devices in response to an unspecified terrorism threat.

A source said the rule would cover a dozen foreign airlines flying from about a dozen countries, including some from the Middle East.