New Delhi, June 13 -- NATO's top military officer is weighing alternative plans to defend Europe should it come under attack from Russia, after the United States announced that it is cutting the number of aircraft and warships that it would provide in a security crisis.

The so-called NATO Force Model is Plan A for making forces from the 32 member nations available in times of peace, crisis or war. It sets out the military assets that commanders can call on in phases over the first six months of any conflict.

But last month, the Pentagon warned its NATO allies that it would be scaling down its commitment to focus on potential threats elsewhere, notably from China in the Indo-Pacific region.

The reduction in available American military a...