U.S. President Donald Trump has said that Pakistan is one of the countries currently testing nuclear weapons. His comments came as discussions continue in the U.S. about restarting nuclear testing after decades.

Trump made the remarks during an interview with CBS News. He said that countries like Russia, China, North Korea, and Pakistan are carrying out nuclear tests, and therefore, he believes the U.S. should do the same.

"We're going to test because they test and others test. And certainly North Korea's been testing. Pakistan's been testing," Trump said.

Trump argued that while other nations test their nuclear systems quietly, the U.S. openly talks about it because it is a democratic country.

"Russia's testing and China's testing, but they don't talk about it. We're an open society. We're different. We talk about it," he said.

Trump claimed that nuclear tests in some countries are carried out deep underground, making them hard to detect. He added that the U.S. should not be the only country to avoid testing.

"They test way under... underground, where people don't know exactly what's happening with the test. They test, and we don't test. We have to test," he said.

The interview followed reports that Russia had recently tested advanced nuclear systems. Trump said the U.S. needs to understand how its own nuclear weapons perform. 

"You have to see how they work," he said.

Trump also claimed the U.S. has the world's largest nuclear arsenal.

"We have enough nuclear weapons to blow up the world 150 times," Trump said.

After Trump’s comments caused concern, US Energy Secretary Chris Wright clarified that the planned tests do not involve actual nuclear explosions.

"These are not nuclear explosions. These are what we call non-critical explosions," Wright told Fox News.

He said the tests will examine the parts of nuclear weapons without triggering the nuclear reaction itself. The goal is to ensure new nuclear systems work properly.

The tests are meant to make sure replacement systems are “better than previous ones,” he added.