Kiev, March 14 : Ukrainian President Volodymyr Zelensky has renewed his call to NATO leaders to establish a no-fly zone over his country, warning that it was only a matter of time that Russian missiles would also fall on the alliance's territories. The President's call on Sunday night came after 30 missiles struck Lviv earlier in the day, while the shelling of the International Centre for Peacekeeping and Security located near the Ukraine-Poland border killed 35 people and injured 134 others. Referring to the shelling of the Centre, Zelensky said that "nothing was happening there that could threaten the territory of the Russian Federation. The NATO border is only 20 kilometres away", reports Ukrayinska Pravda. "Last year, I clearly warned NATO leaders that if there were no harsh preventive sanctions against the Russian Federation, it would go to war. We were right. "Now I am repeating again: if you do not cover us with a no-fly zone, it is only a matter of time before Russian missiles fall on your territory, on NATO territory, on the homes of NATO states' citizens," the President added. A no-fly zone refers to any region of airspace where it has been established that certain aircraft cannot fly. It can be used to protect sensitive areas, such as royal residences, or brought in temporarily over sporting events and large gatherings. The US has ruled out a no-fly zone over Ukraine because it could mean NATO forces shooting down Russian aircraft to clear the skies, the BBC reported. US President Joe Biden said do so would lead to an escalation, which he described as "World War Three". UK Defence Secretary Ben Wallace has also confirmed that his country would not help enforce a no-fly zone over Ukraine because fighting Russian jets would trigger a "war across Europe". /IANS