Putin Says He "Hopes" To Meet Trump For "Necessary Talks"

Russian President Vladimir Putin said Saturday he had explained his position in the Ukraine crisis to US leader Donald Trump at a G20 summit, and remained open to proper talks.

Trump had cancelled a scheduled bilateral meeting with Putin in Argentina, but White House spokeswoman Sarah Sanders said the two did have an "informal" conversation when they crossed paths at a summit dinner Friday.

Putin, briefing reporters after the summit concluded, characterised the encounter as more significant.

"We spoke standing up. I replied to his questions about the incident in the Black Sea," Putin said, after Russia seized three Ukrainian vessels and their crews off Crimea.

"It's a pity that we weren't able to have a real meeting. I think that one is really necessary. I hope that we can meet when the US side is ready for it," he said.

"The questions that we have to discuss are very important. They are above all questions about strategic stability, questions about non-proliferation of weapons of mass destruction."

Tensions spiked on November 25 when Russian forces opened fire on and seized the three Ukrainian navy vessels, detaining the 24 crew members.

It was the first open military confrontation between the rivals since 2014, when Russia annexed Ukraine's Crimea peninsula and pro-Russian separatists in the east entered into conflict with Ukrainian forces.

Trump called off his G20 bilateral with Putin ostensibly because Russia has failed to return the ships and their crews to Ukraine.

But US critics of the president linked the cancellation to new revelations emerging in an investigation into Trump's links to Russia including his past business dealings.

US officials have gone further than Trump himself in condemning Russia's actions.

Defense Secretary Jim Mattis earlier Saturday blasted Moscow over the Russian navy's "brazen" violation of a waterway treaty with Kiev and the seizure of the vessels. 

Speaking of a 2003 agreement governing the Kerch Strait between the Azov Sea and Black Sea, Mattis said Moscow had shown "brazen contempt and dismissal" for the deal "that allowed both Russian and Ukrainian ships free passage."