More: Three officials with knowledge of Defense Department assessments told The Washington Post on Thursday that the lopsided effort "underscores the extent to which Washington has shouldered the burden of countering Iranian ballistic missile strikes during Operation Epic Fury."

U.S. forces, according to those assessments, have used up to half their total inventory of certain high-altitude interceptor systems, while Israel has deployed its own at a slower rate.

"The numbers are striking," Kelly Grieco, a senior fellow at D.C. think tank the Stimson Center, told the Post.

"The United States absorbed most of the missile defense mission while Israel conserved its own magazines," she went on, adding that the rate of use had left production unable to "keep pace with demand."

The situation has apparently sparked alarm among American allies in Asia, particularly South Korea and Japan, which depend on U.S. anti-missile defense systems to deter attacks from hostile states such as China and North Korea.