The Scotland manager was speaking on the eve of tonight’s hastily arranged friendly clash with Poland.
The fixture has replaced the sold-out play-off following the Russian invasion of Ukraine. Today marks a month since President Putin ordered the military assault.
Clarke stressed that the Scots would have to be guided by “Fifa, Uefa and more importantly Ukraine themselves”. He acknowledged that a further postponement of the fixture to the next international window in August/September, just months before the World Cup is due to begin in Qatar, could be required.
“Yes. That’s the easiest way to say it, yes,” he answered when asked if Scotland would simply have to accept another delay.
The draw for the World Cup finals is taking place next week with Scotland’s name being included alongside Ukraine’s and the winner of tonight’s play-off between Wales and Austria.
“I would imagine everyone is waiting until this round of matches is out of the way and then see how the situation develops,” said Clarke. “But obviously, it’s not looking great at this moment.
“If you’re asking me now will the game go ahead in June then it’s going to be difficult. But it’s a situation we can’t control so I’ll focus on these two friendlies and make sure we get something out of the games in this camp.
“Then, maybe in April, we can all sit down together, look at the schedule and how it’s going to pan out for us.
"If you look at it and you’re honest about the situation now then, yes, it’s difficult to see how we’ll be playing them in June," he continued. "It’s not just about the fixture, it’s the fact that they need to get together, have a training camp and get all their players on the pitch with a proper period of time to prepare for such an important game.
“Andriy Shevchenko, who I know from my time at Chelsea, spoke quite well about the situation and said they would want to play on the pitch.
“But the way the situation is I think they should get as much time as possible to try to make that game happen - Scotland against Ukraine at Hampden.”