The Kremlin on Thursday said it was surprised to learn that a meeting between Russian President Vladimir Putin and President Donald Trump had been cancelled via a tweet.

Trump and Putin were supposed to meet in Argentina on the sidelines of the G20 summit, which gathers leaders from the world's 20 largest economies.

But on Thursday, Trump tweeted that the meeting was off because of escalating clashes between Ukraine and Russia near Crimea.

The Kremlin said Trump's tweet was how it learned about the abrupt cancellation.

Kiev and Moscow continue to trade barbs, amid accusations of a large-scale Russian invasion of Ukraine.

The Kremlin on Thursday said it was surprised to learn that a meeting between its leader Vladimir Putin and President Donald Trump had been cancelled via a tweet.

Trump and Putin were supposed to meet in Argentina on the sidelines of the G20 summit, which gathers leaders from the world's 20 largest economies.

It would've been the first meeting between the two heads of state since they met face-to-face in Finland with only their translators present in July.

But on Thursday, Trump tweeted that the meeting had been cancelled in response to news that Russia had fired at several Ukrainian ships on Sunday and were still holding three Ukrainian sailors.

"Based on the fact that the ships and sailors have not been returned to Ukraine from Russia, I have decided it would be best for all parties concerned to cancel my previously scheduled meeting in Argentina with President Vladimir Putin," Trump wrote.

"I look forward to a meaningful Summit again as soon as this situation is resolved!" he added.

The Kremlin said Thursday's tweet was the first time it was given notice about the abrupt cancellation.

"So far, we have only seen the tweet and media reports," Kremlin spokesman Dmitry Peskov told the state-owned Tass News Agency. "We have no official information."



Peskov said if the meeting was indeed cancelled, Putin would have "a couple of additional hours" freed up "for useful meetings."

Trump's tweet appeared shortly after he boarded Air Force One to depart for the summit. White House press secretary Sarah Huckabee Sanders told reporters that Trump made the decision after consulting with Secretary of State Mike Pompeo, chief of staff John Kelly and national security adviser John Bolton.

Trump said earlier on Thursday that the meeting would "probably" still go ahead despite the major escalation of tensions near Crimea.

"They would like to have it. I think it’s a very good time to have the meeting," Trump told reporters before leaving Washington to fly to Buenos Aires.

Tensions remain high in the Sea of Azov — which both Ukraine and Russia share access to — following Sunday's clashes. Ukraine on Monday imposed martial law in parts of the country and accused Russia of planning a full-scale invasion of the country. On Thursday, Kiev called on NATO to deploy ships in order to "provide security" in the tense region.

Ukraine has also accused Russia of enforcing a de facto blockade on two key Ukrainian ports in the Sea of Azov, which Russia denied, saying shipping delays were due to "bad weather."