"We cannot exclude this idea of separate from Ukraine … We can resolve it, but, you know, in a civilized manner."
A referendum is set to be held on Sunday in Crimea. Western leaders have condemned the process and will not recognize the result of the vote.
Ambassador Prystaiko told host Evan Solomon on The House that Crimea is very different from other parts of Ukraine, including a population made up of many Russians with strong ties and loyalties to Russia. He said as a general idea, if the people of Crimea want to live separately from Ukraine, he would support it.
The ambassador said what is happening now in Crimea is not legal, but there are options available for Crimeans if the majority of the population truly wants to separate from Ukraine, and the promise of a legitimate referendum could de-escalate the crisis.
"We have the legal mechanism … if they want to split up from Ukraine. This legal mechanism is a nation-wide referendum. If they want to do this, there is an open way for this," Prystaiko said.
"I don't want to talk about this with Russians, I would love to talk about it with Crimeans," he said.
Foreign Affairs Minister John Baird said now is not the time to have the conversation about a legal referendum in Crimea, but said "the government of Ukraine are at their core democrats."
"I think the prime minister of Ukraine has made a wide-ranging number of propositions and suggestions, but obviously it's awfully hard to move forward with a dialogue when you're under occupation and evoking this stunt of a referendum — an illegal referendum," Baird said.
Fear of military invasion
The ambassador also raised alarm bells over the possibility of a full Russian invasion of Ukraine after Sunday's referendum.
"We are talking about full-scale military invasion. Not just to Crimea, but possibly to the other side of Ukraine," he said.
Russian Foreign Minister Sergei Lavrov ruled out a Russian invasion into Eastern Ukraine after meeting with U.S. Secretary of State John Kerry in London on Friday. Russia will respect the results of the referendum in Crimea and maintains it has the responsibility to intervene in Eastern Ukraine in defence of ethnic Russians who it claims are under threat.
In any case Prystaiko, despite being a diplomat, said he is not afraid to pick up a gun and fight for his country if necessary.
"I'm just doing this job. If I have to do another job, even protecting my country with a gun, I'll do it."