RBS chief Ross McEwan has vowed to press on with plans to close more than 50 branches in Scotland despite public anger.
Mr McEwan told Westminster's Scottish Affairs Committee that he recognised the disappointment of customers facing bank closures but the decision was the "best way of going forward".
The bank, which is majority-owned by the taxpayer, announced in December it would close 62 branches across Scotland, later giving a temporary reprieve to 10 of these until the end of 2018 for review.
Mr McEwan told MPs that the size of the Scottish network would not be reviewed again until at least 2020, but that there was no further opportunity for reprieve for the 52 facing closure.
Committee convener Pete Wishart asked what he would say in response to the "disappointment, frustration and anger" of those communities who would lose their local facility.
Mr McEwan said he accepted "change is absolutely difficult", adding "I do recognise that customers are very disappointed that their local branch is closing".
He said: "What we've done here with a package of different ways of operating with this bank is, I think, the best way of going forward, that we can keep those services to our customers as well as moving away from physical distribution when it's just not being used."
He added: "We've not taken any of these closure decisions lightly.
"Let's be clear, when we look at our customer behaviour the evidence is stark.
"Branch use has fallen dramatically - the great majority of our customers want to bank when it suits them and at all hours.
"They aren't using a branch as their first point of call now at all. We have to respond to changing trends and we have to invest in a range of services to give customers what they want and what they expect.
"We will make a final decision on the 10 branches under review by the end of this year.
"Setting them aside, I am comfortable with the size of our branch network in Scotland and I think it is right alongside all of our other services.
"I want to be clear our branches do remain a core part of our service and we will not look at the size of the network again in Scotland until at least 2020 to give customers, colleagues and the communities greater certainty."
MPs were told that, contrary to claims by the Unite union that there would be 179 compulsory job cuts, there would be a maximum of 12 compulsory redundancies at the affected branches.
The committee also heard that no external reviewer has yet been appointed to carry out the review of the 10 branches offered a reprieve, despite it due to take place between June and August.
Mr McEwan denied that they were being "set up to fail" and insisted that he would take the recommendation of the review.
Mr Wishart asked: "Is there any chance or prospect of having another look at this again, given all the things that you've heard and all the anger and disappointment there is in these communities?"
Mr McEwan said: "We are reshaping this bank and our view was to reshape it in a way that we gave lots of other alternative services to customers.
"So yes, we are closing a number of branches and they will go ahead.
"We will review the 10 and we will seriously review those 10 - it's not an olive branch we're putting out.
"But we do need to push this organisation forward as customer behaviour is changing quite dramatically."