Donald Trump has been branded "ignorant and irresponsible" by a former UK defence minister after refusing to rule out using nuclear weapons to attack Europe.
The US presidential hopeful insisted he would not "take any cards off the table" and said there could "possibly" come a time when they would need to be used.
Labour's John Spellar, a defence minister under Tony Blair and a member of the defence select committee, said the comments were "stupid" and warned it would be "dangerous" if he enters the White House.
The Warley MP said: "Clearly he has no understanding of defence and security and this is completely irresponsible.
"That is why it is so important that he doesn't win the presidential election of our greatest ally.
"It's stupid. It would be dangerous if he did get in.
"This is both ignorant and irresponsible and I hope the American people will ensure that he will never have that responsibility."
Mr Trump, who is vying to win the Republican presidential nomination, made the comments during an interview with Chris Matthews on MSNBC in the United States.
"Would there be a time when it could be used? Possibly," he said.
Mr Trump was told that Prime Minister David Cameron would hear the comments and that no one wanted such a prospect to be raised.
"Then why are we making them?", he replied.
Pressed to say he would not use nuclear weapons in Europe, he said: "I'm not going to take it off the table."
After an incredulous Mr Matthews asked if he might use them in Europe, Mr Trump replied: "No, I don't think so but I am not taking cards off the table."
SNP defence spokesman Brendan O'Hara said: "These comments are chilling and show how outlandish Donald Trump's world view is.
''It also goes to the issue about the UK's nuclear deterrent -Trident is already horrific enough without Donald Trump's finger on our trigger.
''We have always known the last thing the UK's independent nuclear deterrent is is 'independent'. It's American. It's designed, manufactured, overhauled and even tested in the United States. The UK itself has admitted that it is inconceivable that the UK would ever use these weapons without the authority of the USA."