Speaking to students in Germany to commemorate the 70th anniversary of the Marshall Plan to rebuild a ravaged Europe after World War II, Mattis said Russia had chosen to challenge the "secure and peaceful" post-war order.
"Of course this will make Russia-US relations more complex," Putin said in an excerpt from an interview due to air in full at 1700 GMT on Rossiya-1 television.
New sanctions bill against Moscow is evidence of 'internal political struggle' in US, President Vladimir Putin says
Speaking at his annual call-in with Russian citizens, Putin, a former KGB officer, said he found Comey's behaviour strange for a security official, after Comey leaked details of his meetings with Trump.
The 41-year-old, whose anti-corruption videos have needled the country's most powerful and drawn a new generation into politics, is bidding to stand in elections against President Vladimir Putin next year.
In interviews with director Oliver Stone, Russian president outlines criticism of alliance
Russian president denies claims Moscow interfered in 2016 presidential poll, despite claims by US intelligence agencies
"Putin expresses his profound condolences for the British people and condemns the terrorist attack carried out hours ago in London," Kremlin spokesman Dmitry Peskov told Russian news agencies.
"Hackers can be anywhere. They can be in Russia, in Asia... even in America, Latin America," he told NBC News, which previewed an interview with the Russian leader that will be broadcast in full on Sunday.
There would be no cease-fire or de-escalation zones, Russian president says
Oil producers within and outside the OPEC cartel last week agreed to extend a November accord to cut crude production by nine months in a move spearheaded by Moscow and Riyadh.
After playing handshake power games with US President Donald Trump at his first international summit last week, 39-year-old Macron hosts the Russian leader in the splendour of Versailles outside Paris.
Since the start of the Ukraine crisis in 2014, Russia has flexed its muscles with a series of war games involving tens of thousands of troops in areas bordering NATO Baltic states.
Philippines need modern weapons to fight militants, Duterte says
In a telegram to Rouhani, Putin "confirmed the readiness to continue active joint work to further develop the Russian-Iranian cooperation partnership," the Kremlin said in a statement.
Chairman of Tatar mejlis says current status of Black Sea minority mirrors deportations of 73 years ago
"If the US administration finds it possible, we are ready to provide a recording of the conversation between Lavrov and Trump to the US Congress and Senate," Putin said during a press conference.
Hundreds of thousands of computers in more than 150 countries have been hit by the ransomware attack, which has been described as the largest-ever of its kind.
Soldiers and military hardware paraded across Red Square in Moscow as the country held its annual pomp-filled celebration of the defeat of Nazi Germany in 1945.
The 2 leaders talked for 1st time since US launched missile strike against Syrian base last month
There was no indication about the topics of discussion for the two leaders. The call was scheduled for 12:30 pm (1630 GMT).