The UK's vote to leave the European Union has significantly damped expectations for monetary tightening by the Federal Reserve as policymakers warn of possible repercussions for the US economy from market turmoil.
Futures trading now suggests the Fed could hold short-term rates until 2018, with the odds of a move as soon as September of this year retreating sharply after the results of the referendum emerged on Friday.
Some market participants have raised the possibility of whether the US central bank would go as far as to reverse its quarter-point rise in December, although given its limited scope for stimulus the Fed would be very wary of expending its firepower prematurely.
The Fed said in a statement on Friday that it would offer dollar liquidity if needed and that pressures in global funding markets "could have adverse implications for the US economy."
Janet Yellen, the Fed chair, said after the Fed's June meeting that a Brexit vote could have an impact on the outlook for monetary policy, in an indication that it would at the least lower the odds of a near-term upward move, and Wall Street economists on Friday were reconsidering their rate rise forecasts.
In the lead-up to the vote the US central bank examined financial institutions to check what their vulnerabilities were, as well as factoring the risk of an exit vote into its June meeting, when it decided to hold rates unchanged.
Further indications of the Fed's assessment of the repercussions could come on Wednesday, when Ms Yellen is due to attend a conference in Portugal.
The key impact on US policy is likely to be felt via financial markets, including the economic risks that would result from a new upward move in the US dollar. Roberto Perli of Cornerstone Macro said the bar for an outright rate cut would be high and that the Fed would need to see a serious risk of recession before taking such a step.
He added: "More than what happens today, what matters for the Fed is where financial conditions and the dollar will be in the weeks and months ahead. If they tighten a lot, then the whole policy stance of gradual rate hikes will be put on hold indefinitely or even reversed in extreme cases - ie if there is a serious risk of recession.
"But if things calm down eventually and the US economy remains on track, the Fed will be extra cautious but will maintain its gradual tightening stance. In that case it's just the timing that shifts further out."
Analysts at Bank of America Merrill Lynch said the decision to exit would add to a "long string of confidence shocks hitting an already vulnerable US and global economy." Brexit would reduce real Gross Domestic Product growth by an average of 0.2 percentage point over the coming six quarters, they estimated, prompting the Fed to delay its next rate rise until December.
Jon Faust, a professor of economics at Johns Hopkins University and a former senior adviser at the Fed, said officials would now want to gauge where the stock market settles and the impact of the turbulence on the US dollar over the coming days. The net effect so far was not "overwhelming" he argued, and did not merit an inter-meeting policy change.
However, if the dollar kept appreciating that would be a bigger concern, he cautioned. The dollar has been a major driver of Fed policy for the past two years, because of the drag that a strong currency has imposed on US exports and inflation, and also because it has injected financial volatility into emerging markets in particular. It has potential to rekindle capital outflows from China and to damage emerging market corporations that have borrowed heavily in dollars.
While analysts said banks were in a better position to withstand the stress than in the 2007-09 financial crisis, investor fears were evident as major lenders in Europe suffered double-digit share price declines.
Michael Feroli, US economist at JPMorgan Chase said on Friday he was delaying his forecast for a Fed rate increase to December from September and modestly trimming growth forecasts for the US. However an upward move as soon as September was still not entirely out of the question, while an outright cut would look "a bit too jumpy," he argued. "What is harder to model is the sentiment and the political fears and how that ripples through the data," he added.
One question that US analysts are already asking is what the mood of the UK electorate says about the possible outcome of the US presidential election in November.
If there is a similarly acute appetite in the US electorate to reject government elites and anger over immigration it could boost expectations about Donald Trump's possible performance in the presidential election, something that could further affect investor and corporate sentiment.