Scotland will be safer in a “dangerous and insecure world” as part of the United Kingdom, according to Prime Minister David Cameron.
The Nato summit is “a time when you reflect on the dangers of our world”, Mr Cameron told journalists in Newport.
An independent Scotland’s future in Nato is a matter of “total confusion”, alongside its membership of the European Union and its currency, he said.
Voters will be asked whether Scotland should be an independent country in a referendum on September 18.
“All questions for what a separated Scotland would have to do are effectively questions for Alex Salmond to answer and I don’t think he has answered them effectively at all,” he said.
“The questions for what the United Kingdom will look like are questions for me and I can answer all of them about how Scotland would fare inside our family of nations.
“I think there is total confusion about whether a separated Scotland would have a place in the European Union or in Nato, or what currency it would use and all the rest of it.
“In terms of the last two weeks of this (referendum) campaign, what I will be wanting to stress is just what a vital and important question this is.
“Of course, it’s a question for voters in Scotland to consider about their future, but I take a very clear loud message from the rest of the United Kingdom, which is that we want you to stay. We care passionately about our family of nations.
“Scotland can make a different choice because the Scottish people are sovereign in this matter, but they shouldn’t be in any doubt that the rest of the United Kingdom passionately want them to be part of our successful family of nations.
“Obviously, at a Nato conference it’s a time when you reflect on the dangers in our world and I don’t think anybody can be in any doubt that we live in a very dangerous and insecure world.
“I would have thought one of the strongest arguments that those of us that want to see the United Kingdom stay together can make is: in that dangerous and insecure world with terrorist threats and other threats, isn’t it better to be part of a United Kingdom that has a top five defence budget and some of the best security and intelligence services anywhere in the world?
“That is part of every single alliance that really matters in the world, in terms of Nato, the G8, the G20, the European Union, a permanent member of the security council of UN.
“To have all those networks and abilities to work with allies to keep us safe, isn’t it better to have those things than to separate yourself from them?”