US President Joe Biden has warned his Russian counterpart Vladimir Putin against the use of chemical or tactical nuclear weapons in the ongoing war with Ukraine that has stretched to more than six months now.
"Don't. Don't. Don't. You will change the face of war unlike anything since World War II," Biden said.
Biden gave an interview to CBS News anchor Scott Pelley at the White House which will be aired on Sunday. Biden's reaction came soon after Pelley asked what the consequences would be if Putin crossed the line.
Biden said: "You think I would tell you if I knew exactly what it would be? Of course, I'm not gonna tell you. It'll be consequential. They'll become more of a pariah in the world than they ever have been. And depending on the extent of what they do will determine what response would occur."
Biden and Pelley discussed a host of issues beyond the war in Ukraine, including the economy and the upcoming midterm elections.
The Biden administration has announced another $600 million in military aid to help the Ukrainian army maintain momentum against Russia.
In the interview for this Sunday's '60 Minutes', Pelley spoke to Biden about Ukraine's recent battlefield success - and the dangers that could arise.
"As Ukraine succeeds on the battlefield, Vladimir Putin is becoming embarrassed being pushed into a corner," Pelley told Biden.
"And I wonder, Mr President, what you would say to him if he is considering using chemical or tactical nuclear weapons."
"Don't. Don't. Don't. You will change the face of war unlike anything since World War II," Biden replied.
Biden also told Pelley about his efforts to avert a national railroad strike. On Thursday, the President had announced that a tentative deal has been reached between the railroads and rail workers' unions after 20 hours of negotiations in the US Department of Labour.
"We brought business and labour together," the President told Pelley.
"One of the things that happen in negotiations, particularly if they've been elongated like these have, is people say and do things where the pride gets engaged as well. And it's awful hard to back off of some of these things. So, what we did was just say, 'Look, let's take a look. Let's take a look at what's happening'.
"You have a good deal being made for labour. Their income is going to go up 24 per cent over the next five years. They've worked out the healthcare piece, they worked out days off. They both sat down, in my view, and they were in the office today saying, 'Well, we finally figured it out. This is fair on both sides.' And it took that time to focus.
"The alternative was just not thinkable. If, in fact, they'd gone on a strike, the supply chains in this country would've come to a screeching halt. We would've seen a real economic crisis," Biden said.
The interview is Biden's first sit-down with '60 Minutes' since being elected President.