Ukrainian President Volodymyr Zelenskyy has said he will continue negotiating with Russia and is waiting for a meeting with Vladimir Putin.

Zelenskyy has repeatedly called for a meeting with Putin. But so far, his requests have gone unanswered by the Kremlin. Zelenskyy said Sunday during his nightly address to the nation that his delegation has a “clear task” to do everything to ensure a meeting between the two presidents.

Read:Russian airstrike escalates offensive in western Ukraine

Zelenskyy said talks are held daily between the two countries via video conference. He said the talks are necessary to establish a cease-fire and more humanitarian corridors. He said those corridors have saved more than 130,000 people in six days.

The humanitarian convoy to the besieged city of Mariupol was blocked Sunday by Russian forces. Zelenskyy said they would try again Monday.

Zelenskyy has also said it is a “black day” after Russia shelled a military base in the western part of his country.

Zelenskyy said in his nightly address on Sunday that Russia fired 30 rockets at the Yavoriv military base. He said the attack killed 35 people and injured 134 injured others.

Read:U.S. journalist killed by attack near Kyiv

The base is less than 25 kilometers (15 miles) from the Polish border. Zelenskyy said he had given Western leaders “clear warning” of the danger to the base. He asked NATO leaders again to establish a no-fly zone over Ukraine. He warned “it is only a matter of time” before Russian missels fall on NATO territory.

Military analysts say the U.S, Britain and their European allies are unlikely to impose a no-fly zone because they believe it could escalate the war in Ukraine into a nuclear confrontation between NATO and Russia.