Russia has long objected to Ukrainian membership of the Western military alliance. This week’s meeting is stirring old arguments.

Maria Zakharova, spokesperson of the Russian foreign ministry, told Al Jazeera on Tuesday: “We had an objective to weaken NATO because the United States, Britain and the entire NATO had an objective to weaken Russia. Just look at their statements for years, they wanted to weaken our country.”

Sergey Lavrov, the Russian foreign minister, warned that Moscow would take “appropriate steps” in the event of “possible NATO enlargement”, adding that his country would protect its “legitimate security interests”.

Addressing reporters in the Russian capital on Tuesday, he said, in comments carried by the Tass news agency, that the Kremlin was struck by the speed at which Finland and Sweden abandoned their long-held principle of neutrality in order to join NATO.

Before invading Ukraine on February 24, 2022, Russia repeatedly warned the Western military alliance against making Ukraine a member, saying it did not want the alliance on its doorstep.

While there is broad consensus among NATO members to support Ukraine’s future membership, some states such as the US and Germany stress that Kyiv’s application can only be seriously considered after Russia’s war ends.

Kremlin spokesman Dmitry Peskov told a regular news briefing: “Russia is perceived by them (NATO leaders) as an enemy, as an adversary. It is in this vein that the discussions (in Vilnius) will be conducted.

“We are monitoring this very carefully, because much of what has been said will be subject to in-depth analysis in order to take measures to ensure our own security.”

At the heart of NATO’s two-day summit is the issue of Moscow’s aggression in Ukraine – and how to counter it.

Hours before it began, Russia attacked Kyiv with Iranian-made Shahed drones and air raid sirens rang out in the capital; Ukraine said it shot all of them down.

NATO chief Jens Stoltenberg said that he expects the group to “send a clear, united and positive message on the path towards membership for Ukraine”, but those comments were not strong enough to satisfy Ukrainian President Volodymyr Zelenskyy, who claimed it was “absurd” that a timeline for joining the alliance was not set.

US President Joe Biden said that Washington and its allies were discussing sending more arms and equipment to Ukrainian forces – pledges that saw Russia baulk.

By announcing more aid plans, the US has signalled a lack of interest in talks to end the war, Russia’s RIA news agency cited senior diplomat Konstantin Gavrilov as saying.

Gavrilov also warned that Europe would be the first to face “catastrophic consequences” if the war escalates.

Ukraine, with some of its country under Russian occupation last year, made the defiant move and formally applied for NATO membership last September.

“De facto, Ukraine is already in the alliance. Our weapons are the weapons of the alliance. Our values are what the alliance believes in … Vilnius must confirm all this,” Zelenskyy said on the eve of the NATO summit.

Meanwhile, Russia’s ambassador to the US, Anatoly Antonov warned of “the most unfavourable outcome” amid a standoff between Moscow and NATO countries.

“The decisions of the West are posing increasingly insurmountable obstacles to a way out of the acutest political and military crisis, fraught with the most serious consequences for international security,” Antonov said on Monday, as quoted by his embassy on Telegram.