BRUSSELS, Jun. 12 (Reuters) - In a rare reference to the Western nuclear arsenal, NATO chief Jens Stoltenberg on Wednesday highlighted the alliance's efforts to adapt its capabilities to current security threats, taking note of Russia latest nuclear rhetoric and drills.

Talking to reporters before a two-day NATO defence ministers' meeting in Brussels that will include a gathering of the alliance's nuclear planning group, he called nuclear weapons NATO's "ultimate security guarantee" and a means to preserve peace.

While it is well known that the U.S. has deployed nuclear bombs to several locations in Europe, NATO rarely talks about these weapons publicly.

Discussing what he called "the ongoing adaptation" of NATO's nuclear arsenal, Stoltenberg said the Netherlands in June declared the first F-35 fighter jets ready to carry nuclear arms and said the U.S. was modernising its nuclear weapons in Europe.

He described increasing Russian activity around its nuclear capabilities. "What we have seen over the last years and months is a dangerous nuclear rhetoric from the Russian side.... We also see some more exercises, nuclear exercises on the Russian side," he said.

On Tuesday, Russia said its troops had started the second stage of drills to practise the deployment of tactical nuclear weapons alongside Belarusian troops after what Moscow said were threats from Western powers.

Since sending thousands of troops into Ukraine on Feb. 24 2022, Russian President Vladimir Putin has repeatedly said Moscow could use nuclear weapons to defend itself in extreme situations.

Russia accuses the U.S. and its European allies of pushing the world to the brink of nuclear confrontation by giving Ukraine billions of dollars worth of weapons, some of which are being used against Russian territory.

Stoltenberg also referred also to the modernisation of China's nuclear weapons, saying Beijing was expected to boost the number of nuclear missiles within a few years and many of them would be able to reach NATO territory.