Florida — After months of promising to engage more with Russia, President-elect Donald Trump vowed to enhance America's nuclear capabilities, admonishing Russian President Vladimir Putin on Friday that he hopes both global powers can restore collaboration so that "we do not have to travel an alternate path".Trump passed along a "very nice letter" that his transition team said was sent to him by Putin urging Trump to act "in a constructive and pragmatic manner" to "restore the framework of bilateral cooperation".The letter, dated December 15, also notes that serious global and regional challenges "show that the relations between Russia and the US remain an important factor in ensuring stability and security in the modern world".In response, Trump said that Putin's "thoughts are so correct," and that he hopes "both sides are able to live up to these thoughts, and we do not have to travel an alternate path".Putin spokesperson Dmitry Peskov confirmed that Putin sent the letter, "voicing hope for an improvement of bilateral ties," according to the Interfax news agency. Trump's transition team described the text as an unofficial translation.The exchange comes on the heels of comments by Trump and Putin alike about the need to strengthen their countries' nuclear arsenals. Trump reopened the debate over nuclear proliferation on Thursday, declaring on Twitter that the US should "greatly strengthen and expand its nuclear capability" until the rest of the world "comes to its senses" regarding nuclear weapons. Those comments echoed an earlier statement by Putin, who said earlier on Thursday that strengthening his country's nuclear capabilities should be a chief military objective in the coming year.But Putin downplayed the significance of Trump's comments at a marathon end-of-year news conference on Friday. Putin said he sees "nothing unusual" in Trump's pledge to strengthen the US nuclear forces, saying the statement is in line with the president-elect's campaign promises.