US President Joe Biden has reacted to the statements of his predecessor Donald Trump admitting he threatened allies to "encourage" Russia to engage in aggression to force them to increase their contributions to collective security.

As reported by The Hill, Biden called Trump's remarks "appalling and dangerous".

He also warned that a potential second Trump term would destroy the USA's international relations and embolden America's enemies.

"Donald Trump’s admission that he intends to give Putin a greenlight for more war and violence, to continue his brutal assault against a free Ukraine, and to expand his aggression to the people of Poland and the Baltic States are appalling and dangerous," Biden said.

He also noted that such remarks are expected from a man "who is promising to rule as a dictator like the ones he praises on day one if he returns to the oval office".

During a rally in South Carolina, Trump reiterated how, during his presidency, he threatened to "encourage Russia" to attack one of the NATO members who do not fulfil their financial obligations to the Alliance.

European Council President Charles Michel called Trump's words irresponsible.

The White House previously said Trump's threats to encourage the Russian Federation to engage aggression against its allies are "abnormal".