Russian President Vladimir Putin says Russia is "stronger than any potential aggressor" because it has modernised its nuclear missiles and other forces.
He also said the US withdrawal in 2001 from the Anti-Ballistic Missile (ABM) Treaty had "created the conditions for a new nuclear arms race". The US-Soviet ABM Treaty was signed in 1972.
On the victory of US President-elect Donald Trump, Mr Putin said "nobody believed he would win, apart from us".
Mr Trump has strongly praised Mr Putin.
The Russian leader covered many topics in his big annual press conference, lasting more than four hours.
He described as "nothing special" Mr Trump's latest call for the US to "greatly strengthen and expand" its nuclear forces. Mr Trump had spoken of that during the election campaign, he noted.
When asked if he would run again in Russia's 2018 presidential election, Mr Putin was non-committal. "I will look at what's going on in the country, in the world," he said.
"It's no secret we've worked hard to improve our missile forces," Mr Putin said.
Since the US pulled out of the ABM Treaty, he said, "we have had to modernise our offensive systems". But he also acknowledged that the US military was the strongest in the world.
"If anyone is unleashing an arms race it's not us," he said. "We will never spend resources on an arms race that we can't afford."
A study of Russia's nuclear forces in the Bulletin of the Atomic Scientists says that - despite Mr Putin's remarks - a budget crunch is imposing delays on the modernisation effort.
Mr Putin dismissed US government allegations about a Russian hand in the hacking of Democratic Party computers during the US presidential election campaign.
"The losing side is looking for people to blame outside. They would do better to look for the problems among themselves."
He noted that the Democrats had lost ground in congressional elections as well. "So that's my work too?" he railed.
"The main thing is the information that these hackers provided... Did they exaggerate anything? No, they revealed true information."
'Many Americans have the same idea'
One journalist told Mr Putin that, according to a survey, 37% of US Republican supporters felt positive about him.
"I don't attribute that finding to myself," Mr Putin responded. "It means that many Americans have the same idea about how the world should be run, how to solve common problems.
"That's a good basis for building relations between our two powerful nations."
'Problems with doping'
When asked about the doping scandal in Russian sport, Mr Putin lambasted the whistleblower Grigory Rodchenkov, who used to head the Russian anti-doping laboratory.
"Do you know where he worked before that?" President Putin said.
"In Canada! And then what did he do? He came to Russia and... kept bringing in all sorts of filth. I can hardly imagine that no-one ever spotted that he was carrying these banned substances across the borders of Canada or the US."
According to Mr Putin, "he turned this into his personal business - he made people take those substances".
Mr Rodchenkov's revelations prompted an investigation by the World Anti-Doping Agency (Wada), which said Russia had operated a state-sponsored doping programme for four years in most Olympic sports.
The scandal led to Russian athletes being banned from athletics and some other events at the Rio Olympics, and from the entire Paralympics.
In May the New York Times interviewed Mr Rodchenko, and he said doping athletes had been part of his job.
Mr Putin admitted that Russia did "have problems with doping" but Russia had "never created the problem of doping", he added.
He said Wada's tests must be "transparent and monitorable". "We need to know who is being tested, what are the substances, the results and what punishment measures are being taken."
"Sport must be cleansed of all politics," he added.