Germany is likely to acquire a missile defence system, along Israeli lines, to protect itself from possible Russian aggression.
Chancellor Olaf Scholz said such a system was "certainly among the things we are discussing, for good reason".
“We must all prepare ourselves for the fact that we have a neighbour now ready to use force to assert its interests,” he told German television on Sunday evening.
According to media reports, talks are under way to buy an adapted version of Israel's Arrow 3 model for intercepting long-range ballistic missiles, at a cost of €2 billion. The system could be in place by 2025 and could be calibrated to protect Germany, Poland and the Baltic countries. The Arrow system is separate to Israel's Iron Dome system, which can intercept low-flying, low-range rockets.
Germany already has limited short-range rocket defences, but relies on the ageing Patriot system for mid-range rocket defences and is dependent on Nato allies for long-range missile defence.
In an hour-long solo talk-show appearance, Mr Scholz warned Russia of "dramatic measures" if it deployed chemical or biological weapons in Ukraine.
“Of course there are considerations at present on those measures but obviously that is not something one talks about,” he said.
Asked about US president Joe Biden's Warsaw remarks, that Vladimir Putin "cannot remain in power", Mr Scholz said: "This is not a goal of Nato and also not that of the American president."
Mr Scholz insisted Germany was expediting its shift away from Russian energy, in particular coal imports, by the end of this year. Stopping gas and oil imports from Russia immediately would cause economic chaos, he said, dismissing suggestions that Germany was underwriting Putin’s war on Ukraine.
“Russia cannot do anything with the money in these accounts because of our sanctions,” he said.
The Social Democrat chancellor, sworn in last December, said the Russian attacks had left him “outraged”.
“It marks the return of imperialism,” he said, vowing that Nato would “defend every inch” of its members’ sovereign territory.
Ukraine's ambassador to Berlin, Andrij Melnyk, a vocal critic of Germany's stance, boycotted a benefit concert for his country on Sunday organised by President Frank Walter Steinmeier. Instead the ambassador told a Sunday newspaper about his talks with various German cabinet members. Defence minister Christine Lambrecht, he said, was "mostly concerned with her public image". Shortly after Russia's invasion, he said finance minister Christian Lindner told him: "You have only a few hours."
The minister reportedly ruled out the ambassador’s request to exclude Russia from the Swift electronic payments system, saying Berlin was planning to work with a Russian-supported Ukrainian government. Mr Melnyk described this as “the worst conversation of my life”.