NATO has stepped up nuclear preparations while warning against the use of devastating nuclear weapons after Russia suffered a string of battlefield defeats.
Repeated threats from within Russia that nuclear weapons could be used has stoked fears in the West.
The number of NATO warships in the North Sea has been doubled to 30 with a focus around key infrastructure after recent suspected attacks on vital gas pipelines.
It remains unclear who was behind explosions last month affecting gas pipelines under the Baltic Sea. Moscow has denied any involvement and pointed the finger at the United States.
Thankfully NATO has not noticed any change in Russia's nuclear posture following the threats, Secretary General Jens Stoltenberg told reporters in Brussels on Tuesday.
Stoltenberg also said NATO allies would meet any attacks on critical infrastructure with a "united and determined response".
The alliance will proceed with its annual nuclear preparedness exercise "Steadfast Noon" next week - in which NATO air forces practise the use of US nuclear bombs based in Europe with training flights - without live weapons.
Ukrainian President Volodymyr Zelenskiy has appealed to leaders of the Group of Seven nations for more air defence capabilities after a string of missile attacks on Ukrainian cities.
On Monday, dozens of strikes killed 19 people, wounded more than 100 and knocked out power supplies across the country in Moscow's biggest aerial offensive since the start of its invasion on February 24.
The strikes came days the partial destruction of the Kerch bridge, which connects Crimea to mainland Russia.
The bridge became a symbol of Russia's commitment to the annexed territory.
Ruling out peace talks with Putin, Zelensjy told G7 leaders: "When Ukraine receives a sufficient quantity of modern and effective air defence systems, the key element of Russia's terror, rocket strikes, will cease to work".
On Tuesday the first of four IRIS-T air defence systems sent by Germany arrived in Ukraine and the White House later said it was speeding up the shipment of sophisticated NASAMS air defenses.
Washington has provided more than $16.8 billion worth of security aid to Ukraine during the war.
The G7 nations, (the US, Germany, France, Japan, Britain, Italy and Canada) have pledged to Ukraine continued "financial, humanitarian, military, diplomatic and legal support...for as long as it takes".
It also condemned "indiscriminate attacks on innocent civilian populations" as war crimes and said Putin would be held to account for them.
