Trump releases Putin letter urging better US-Russia ties

US President-elect Donald Trump on Friday released what he said was a "very nice" letter from Russia's President Vladimir Putin calling for a thaw in ties between the rival powers.

Relations between Washington and Moscow are at their worst since the end of the Cold War, and President Barack Obama has imposed sanctions over Russia's interventions in Syria and Ukraine.

But Trump, who takes office on January 20, called several times during his election campaign for improved relations and suggested he could work with Putin to jointly oppose Islamist extremism.

Putin's letter, according to a translation released by Trump's office, said "relations between Russia and the US remain an important factor in ensuring stability and security of the modern world."

And "it called for real steps to restore the framework of bilateral cooperation in different areas."

Trump responded by declaring: "A very nice letter from Vladimir Putin; his thoughts are so correct.

"I hope both sides are able to live up to these thoughts, and we do not have to travel an alternate path," Trump said, a day after both he and Putin vowed to boost their country's nuclear arsenals.