Teams from Ukraine and Russia are in Istanbul ahead of a fresh round of peace talks.
A number of options for a ceasefire are on the table, including for Ukraine to remain neutral - but both sides are playing down hopes of a breakthrough.
Negotiations were delayed yesterday and today's talks are the first to take place in two weeks.
Ukraine's foreign minister Dymytro Kuleba told teams not to eat or drink anything.
He said, "preferably, do not touch anything" amid poisoning concerns.
It's claimed two Ukrainian negotiators and Russian oligarch Roman Abramovich were poisoned earlier this month.
Investigative website, Bellingcat says the owner of Chelsea football club experienced "piercing pain in the eyes".
But US intelligence has cast doubt on the claims, suggesting they may have caused by environmental issues instead.