One of the main motorways into Belfast will be shut on Monday morning - at rush hour - for the arrival of Barack Obama.
The M2 citybound will be closed from 8.15am to 9am from Templepatrick.
The US President will be speaking to a crowd in the Waterfront Hall and the Secret Service is taking no risks to protect the world's most powerful man.
Oxford Street will also be closed to all traffic from 8.30 to 10.30am.
The M2 closure will affect all traffic seeking to join the M2 at Templepatrick, Sandyknowes, Fortwilliam and the M5 from 8.15 to 9am.
And on the Sydenham Bypass citybound traffic will be affected between 8.30 and 9.30am.
Motorists have been warned to expect major disruption.
Commuters are being asked to make their journey to work earlier than usual or to use public transport to avoid congestion.
Anyone travelling to a hospital appointment, or who is catching a flight from George Best Belfast City Airport on Monday morning, is advised to leave early.
Regional Development Minister Danny Kennedy said: "It is very likely that there will be major disruption to city centre traffic on Monday morning, potentially for a number of hours
"Our advice is that people should only travel into Belfast on Monday morning if they have to.
"For those that do, my strong advice is to plan to be in work or school before 8am or travel later and, if at all possible, use public transport.
"Translink has arranged extra capacity on buses and trains to cope with any additional demand and the availability of bus lanes means that such services are likely to face less delays than general traffic.
"Finally, for those people intending to travel to the airport ensure that you plan to arrive early, and check in advance with your airline that there are no problems expected."