U.S. President Donald Trump on Thursday abruptly canceled a planned two-hour meeting with Russian President Vladimir Putin in response to Moscow's seizure of Ukrainian ships in the Black Sea region.
"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," Trump said on Twitter as he left Washington for Buenos Aires and the weekend G-20 summit of heads of the world's leading economies.
"I look forward to a meaningful Summit again as soon as this situation is resolved!" Trump added.
Trump tweeted about canceling the talks with Putin not long after telling reporters at the White House that the meeting would likely proceed as planned.
"I probably will be meeting with President Putin," he had said. "They would like to have it. I think it's a very good time to have the meeting."
But he said he would get a final report during his flight concerning the Russian seizure Sunday of the three vessels and their crews in the Kerch Strait as they tried to make their way to the Ukrainian port of Mariupol, in the Sea of Azov.
"I'm getting a full report on the plane as to what happened with respect to that and that will determine what I'm going to be doing," he said.
The White House said Trump made the decision on board Air Force One after conferring with Secretary of State Mike Pompeo, National Security Adviser John Bolton and White House Chief of Staff John Kelly.
Russian news agencies reported the Kremlin had not been notified in advance of Trump's decision. The Russian embassy in Washington said that if Trump and Putin aren't going to meet, then the Russian leader "will have a couple of additional hours on the program for useful meetings."
Request for NATO aid
Meanwhile, Ukrainian President Petro Poroshenko asked NATO countries to send naval ships to the Sea of Azov to aid his country and "provide security" amid tensions with Russia. Ukraine, once a Soviet satellite state, is not a NATO member.
Poroshenko's comments were published Thursday in the German newspaper Bild.
NATO spokeswoman Oana Lungescu responded to Poroshenko's request by saying the military alliance already has a strong presence in the Black Sea region.
She said NATO ships routinely patrol the area and several NATO allies conduct reconnaissance flights over the region. "We will continue to assess our presence in the region," Lungescu added.
German Chancellor Angela Merkel also rejected Poroshenko's request, urging Kyiv to adopt a "sensible" approach "because there is no military solution to these disputes."
Also Thursday, Turkish President Recep Tayyip Erdogan said he could play a mediator role between Ukraine and Russia.
Erdogan has held phone talks with leaders on both sides, and said he would continue discussing the issue with Putin and Trump at a G-20 summit.
Ukraine said Russia used a tanker to block access to the Kerch Strait, which under a treaty is shared territory. Russia said the vessels illegally entered its waters.
Putin on Wednesday blamed Poroshenko for the incident, alleging it is an attempt by Poroshenko to boost his re-election chances next year.
Ukraine has imposed martial law in some of its border regions in response to the incident, and with a growing number of other European countries, urged Western allies to impose additional sanctions on Moscow.
Poroshenko said martial law will help "strengthen Ukraine's defense capabilities amid increasing aggression and according to international law, a cold act of aggression by the Russian Federation." He demanded Russia release the Ukrainian sailors and vessels.
The U.S. special envoy for Ukraine, Kurt Volker, told reporters Wednesday in Berlin he believes Kyiv's account that its ships were operating within global maritime rules.
Volker said the Ukrainian vessels were returning to Odessa "when the Russian vessels then pursued them and attacked them."
Ukrainian officials have released what they maintain is the precise location where its ships were fired upon.
Volker said he has not received independent U.S. verification of Ukraine's information, but believed "the data the Ukrainians have provided is quite clear."
Poroshenko wrote Thursday on Twitter that his country will impose unspecified restrictions on Russian citizens in response to Russia's actions. Ukraine has already denied Russians entry into the country since last week's incident.
Russia annexed the Crimean Peninsula in March 2014, saying its ethnic Russian majority was under threat from the Ukrainian government. A month later, it fomented a pro-Russia separatist rebellion in eastern Ukraine in an ongoing conflict that to date has claimed more than 10,000 lives.
Ukraine and the West repeatedly have accused Russia of fueling the conflict by providing rebel forces with weapons and other support, a charge Moscow has denied despite strong evidence to the contrary.