Ukraine would like U.S. President Donald Trump to be present at a potential meeting between President Zelensky and Russian President Vladimir Putin, Foreign Minister Andrii Sybiha told journalists.

Vladimir Putin and Volodymyr Zelensky could come face to face in Turkey this week - but it wouldn't be the first time the world leaders have met in person.

The president said he's optimistic about Thursday's expected talks between Vladimir Putin and Volodymyr Zelensky in Istanbul.

The Kremlin said Saturday a meeting between Russia's Vladimir Putin and Ukraine's Volodymyr Zelensky would be possible only after both sides reach an agreement, a day after the first direct talks between the two countries in more than three years.

The topic of direct, high-level contact between Russia and Ukraine was raised during Monday’s phone call between Russian President Vladimir Putin and U.S. President Donald Trump, Kremlin spokesman Dmitry Peskov said,

President Volodymyr Zelensky said he will meet with Turkish President Recep Tayyip Erdogan in Ankara, but said both leaders are ready to fly to Istanbul if Russian President Vladimir Putin chooses to attend the talks there.

Ukrainian President Volodymyr Zelensky accused Russian President Vladimir Putin of being too "afraid" to turn up for face-to-face peace talks in Istanbul as direct negotiations erupted in accusations that Russia made "unacceptable demands."

That meeting wasn’t going to take place,” Trump told reporters Monday. “I insisted that that meeting take place, and it is taking place.”