Sikorski’s remarks come after a suspected Russian drone crossed into Polish airspace last week during a large-scale Russian airstrike that targeted multiple regions in Ukraine, including areas close to the Polish border.

Polish authorities have since been searching for the UAV.

This was the fifth such violation of Polish airspace by Russia since the full-scale war in Ukraine started in February 2022.

Speaking to the British newspaper The Financial Times, Sikorski stressed that Warsaw’s NATO membership does not override its duty to protect its own citizens.

He said: “Membership in NATO does not trump each country’s responsibility for the protection of its own airspace—it’s our own constitutional duty.

“I’m personally of the view that, when hostile missiles are on course of entering our airspace, it would be legitimate self-defense [to strike them] because once they do cross into our airspace, the risk of debris injuring someone is significant.”

He added that Ukraine has posed no objection to this.

In July, Poland and Ukraine signed a bilateral security agreement that allowed for the possibility of intercepting missiles and drones in Ukrainian airspace fired toward Poland.

Donald Tusk, the Polish Prime Minister, stressed that such a policy would only be implemented if it had complete support within NATO.

However, Jens Stoltenberg, the alliance’s outgoing secretary-general, rejected the proposal, fearing that it could embroil NATO directly in the Ukraine war.

Ukraine’s Kursk offensive

Speaking of Ukraine’s incursion into the western Russian region of Kursk, Sikorski admitted that while it is too early to gauge the military success of Kyiv’s offensive, the operation sends a powerful message to Vladimir Putin, showing that “the victim doesn’t always do what you expect.”

He added: “Not just Ukraine but the entire West should keep Putin off balance, and one of the mistakes that our side has made consistently is telling Putin in advance what we will or we will not do—and that is why the result of this [Kursk] foray is so far better than the counteroffensive last year, which was so plain to anticipate and therefore to prepare for.”

Sikorski also said that with the U.S. presidential election approaching in November, European leaders need to make a stronger case to both the American public and its politicians that Europe is actively engaged in international security, rather than lagging behind.

“We have a good story to tell: not only are we spending more on defense, but we are actually spending more on Ukraine than the United States,” he said, referring to Europe’s combined military, financial, and humanitarian support to Kyiv.