President Lukashenko issued the warning after President Putin said on September 25 that Russia needed to update its nuclear doctrine to clearly define situations that could prompt Moscow to launch a nuclear attack.

Mr Putin stressed that Moscow would also "consider" a nuclear response if it received "reliable information" about a massive missile strike by another country targeting Russia or its closest ally, Belarus.

"As I said at the patriotic forum [on September 17], an attack on Belarus will cause World War III. Recently, [President] Vladimir Putin confirmed that the country has revised its nuclear doctrine. An attack on Russia and Belarus will cause a nuclear reaction. He confirmed what I said. That is the main point of my statement," President Lukashenko said during a talk with students at a university in the Belarusian capital Minsk on September 27, according to BelTA News Agency.

"As soon as they attack us, we use nuclear weapons. Russia will protect us. If we use nuclear weapons, they will do the same and also against Russia. Therefore, Russia will use its entire arsenal. This will be a world war. The West does not want this... We tell them directly: the red line is the border. You step on it, we will react immediately," Mr. Lukashenko continued to emphasize.

According to Mr. Lukashenko, NATO countries are said to have deployed troops on the border with Belarus, especially in Poland.

On the other hand, President Lukashenko called for: "There are certain boundaries, limits. We need to negotiate with the Ukrainians, we need to end this conflict." He believes that good relations between the two peoples will be rebuilt over time, according to BelTA.