No One
My understanding is that due to its overall economic conditions today, Russia, a country much weaker than Soviet unx, does not have enough military power to defeat NATO in a hot war without invoking nuclear weapons (e.g., the military budget of Russian is ~$70 billion, compared with ~$700 billion military budget for U.S), although they might have the motivation to start one. See here for NATO's military budget.
I believe there are many ways for NATO to confront Russia. For example, if there are cyber-attacks from Russia, simply fight back with cyber techniques. Sanctions are also good tools to use.
However, the enlargement of NATO in the recent years seemed to raise the risk of hot war with Russia. For example, NATO tried to build missile defense complex in Poland and even trying to include Ukraine, neighbor of Russia into their organization. What is their motivation of doing so?
Why can't NATO simply let the Eastern Europe stay (at least militarily) neutral between NATO and Russia? What is the motivation of their expansion in Eastern Europe, irritating Russian, and at the cost of a potential Russia-Ukraine war which could involve NATO themselves?

我的理解是,鉴于俄罗斯如今的整体经济状况,它是一个比苏联弱得多的国家,在不用核武器的情况下,没有足够的军事力量在热战中击败北约(例如,俄罗斯的军事预算约为700亿美元,而美国的军事预算约为7000亿美元),所以北约可能会有故意挑起战争的动机。北约的军事预算自己搜。
我认为北约有很多方法来对抗俄罗斯。例如,如果俄罗斯发动网络攻击,就用网络技术进行反击。制裁也是很好的手段。
然而,北约近年来的东扩似乎增加了与俄罗斯爆发热战的风险。例如,北约试图在波兰建立导弹防御系统,甚至试图将俄罗斯的邻国乌克兰纳入组织。他们这样做的动机是什么?
为什么北约不能让东欧在北约和俄罗斯之间保持(至少在军事上)中立呢?他们在东欧扩张、激怒俄罗斯,并以可能引发涉及北约自身的俄乌战争为代价,其动机是什么?