The NATO member's top diplomat spoke after the Western defence alliance agreed to massively ramp up defence spending, seen as vital to counter the threat from Russia.

"Putin should understand that he is on the path of (Soviet leader Leonid) Brezhnev. He himself once said that the Soviet Union collapsed because it spent too much on armament, and now he is doing exactly the same thing," Sikorski said in an interview with AFP, the Polish news agency PAP and German agency DPA.

"He is waging a very expensive war... scared the whole West into reinforcing its defence spending," Sikorski said, adding: "We are doing it because Putin is threatening us".

"This means that from an economy the size of Texas, Putin will have to squeeze out even more defence funds. Hopefully with a similar result for the regime (to that of the Soviet Union), but faster."

NATO's 32 countries agreed to US President Donald Trump's headline target of five percent of GDP on defence spending following two days of talks in The Hague.

The compromise hatched by NATO sees countries promise to dedicate 3.5 percent of GDP to core military spending by 2035, and a further 1.5 to broader security-related areas such as infrastructure.

Underpinning the leaders' discussions on defence was Moscow's invasion of Ukraine, with the summit's final statement referring to the "long-term threat posed by Russia to Euro-Atlantic security".

Trump also signed off on a final declaration confirming an "ironclad commitment" to NATO's collective defence pledge that an attack on one is an attack on all -- a reassuring move for European countries worried about Russia.

- 'Trump understands' -

Fearing threats from neighbouring Russia, Poland has for several years rapidly modernised its military, with a string of arms contracts, mainly with the United States and South Korea.

It has already earmarked 4.7 percent of its GDP for military expenditure this year, and next year it aims to raise it further.

Sikorski said "Trump understands now that it is Russia that does not want an end to the war" in Ukraine, which began with Russia's invasion in February 2022.

He said that at the NATO summit, "I drew attention to the fact that this shows a lack of respect on the part of Vladimir Putin towards the peace initiatives of President Trump".

Sikorski also hailed Germany -- Europe's biggest economy -- for its efforts to boost its military.

This week Germany revealed plans to reach the 3.5 percent level for core spending six years early, in 2029, with the vast extra outlays necessary made possible after the country eased its rules on taking on debt.

Chancellor Friedrich Merz has vowed to build Europe's "strongest conventional army" to counter the growing threat from Moscow.

Sikorski said "we are good allies and we need to build a kind of force that will not scare anybody but that will deter Putin".

"And I would see the need to counter the Russian missile threat from the Kaliningrad exclave as an urgent Polish-German challenge," he added.

Poland shares a border with Russia's heavily militarised Kaliningrad exclave.