KYIV, March 13 - Russia escalated attacks in western Ukraine on Sunday with a deadly airstrike on a military base where Ukrainian troops had trained with NATO forces, bringing the conflict closer to Poland and prompting Ukrainian President Volodymyr Zelenskyy to renew his pleas for a no-fly zone, The Associated Press reported.

Zelenskyy called Sunday a “black day,” and said none of the activities at the military base would have threatened Russian territory. An American journalist was also killed Sunday and another injured when their vehicle came under fire from Russian forces outside Kyiv. Meanwhile, continued fighting in multiple regions caused more misery throughout Ukraine and has provoked international outrage.

Now in its third week, the war has forced more than 2.5 million people to flee Ukraine. Thousands of civilians and soldiers have been killed.

Ukrainian officials said at least 35 people were killed and 134 wounded Sunday when more than 30 cruise missiles were fired at the Yavoriv military range, just 25 kilometers (15 miles) from the Polish border.

The training base appears to be the most westward target struck so far in the 18-day invasion. The facility, also known as the International Peacekeeping and Security Center, has long been used to train Ukrainian military personnel, often with instructors from the United States and other NATO countries.

The base has also hosted international NATO drills. The site symbolizes what has long been a Russian complaint: That the 30-member NATO alliance is moving closer to Russia’s borders. Russia has demanded that Ukraine drop its ambitions to join NATO.

After the attack, White House national security adviser Jake Sullivan said on CBS News’ “Face the Nation” that NATO will respond if Russian attacks hit NATO countries.

Zelenskyy said he had told Western leaders that the base was in danger and he again asked NATO to establish a no-fly zone over Ukraine.

“If you do not close our sky, it is only a matter of time before Russian missiles fall on your territory. NATO territory. On the homes of citizens of NATO countries,” Zelenskyy said. Military analysts have said a no-fly zone is unlikely because the U.S. and its allies believe it could escalate the war.

Russian airstrikes also again hit the airport in Ivano-Frankivsk, another city in western Ukraine south of Lviv and 250 kilometers (155 miles) away from Ukraine’s border with NATO members Slovakia and Hungary. The city’s mayor, Ruslan Martsinkiv, said Russia’s goal was “to sow panic and fear.” (ap/ez)