Former Defense Secretary Donald Rumsfeld used to call his one-page, often one-sentence, action memos “snowflakes,” because they fell from above, and each one was different. This month and next, the Pentagon will be hit with a blizzard of new reports, all attempting to identify and quantify threats and outline strategies to counter and defeat them.

Here is your field guide for telling them apart:

The National Security Strategy: This is the only one of the major strategy documents that has already been released. Completed in record time under the direction of national security adviser Lt. Gen. H.R. McMaster, the strategy is a broad umbrella mission statement that describes all instruments of national power — military, diplomatic, and economic. It also sets out four main goals: protecting the homeland, promoting American prosperity, preserving peace, and advancing American influence.

McMaster says Trump’s NSS is based on “principled realism” and a clear-eyed view of the world as it is, not as some might wish it to be.

The National Defense Strategy: The Pentagon issues its own master strategy mission statement next Friday. “There will be a classified one that is relatively thick,” Defense Secretary Jim Mattis told reporters last week, “There will be a shorter one that will basically lay it out, unclassified.”

The NDS is a more defined focus on the U.S. military's role in carrying out the president’s agenda. In previous administrations, this document was called the Quadrennial Defense Review, which was mandated by Congress, and made public. But Congress scrapped that requirement in 2017, responding to criticism that it was a watered-down consensus document for public consumption, as opposed to providing real guidance.

The Nuclear Posture Review: Late this month, the Pentagon will release the results of its year-long review reassessing nuclear policy, capabilities, and employment concepts. While much of the U.S. doctrine is highly sensitive, the likely major bullet points are already in the public domain thanks to leaked drafts and public statements.

Pentagon officials, including Mattis, have voiced strong support for maintaining and modernizing all three legs of the nuclear triad: submarines, bombers, and land-based missiles. And last March, Gen. Paul Selva, vice chairman of the Joint Chiefs of Staff, told Congress one imperative was to reverse the two-decade policy aimed at reducing the number and types of U.S. nuclear weapons.

A draft of the new policy calls for enhancing “the flexibility and range of its tailored deterrence options,” with several low-yield variants of existing nuclear bombs and warheads. After a draft was leaked, the Pentagon said several drafts have been written amid the building's "robust" discussions.

"[T]he Nuclear Posture Review has not been completed and will ultimately be reviewed and approved by the President and the Secretary of Defense," the statement said. "As a general practice, we do not discuss pre-decisional, draft copies of strategies and reviews."

The Ballistic Missile Defense Review: This review is expected to be released next month. Against the backdrop of increasingly aggressive and credible threats from North Korea to lob a nuclear-tipped missile at the continental U.S., this review will examine the effectiveness of America’s multi-layered missile defenses, and make recommendations about how to make the shield more reliable and effective. The BMD review could determine where and how billions of defense dollars are spent.

The Bio-Defense Review: This is another congressionally-mandated document that not only involves the Pentagon but also Homeland Security, Health and Human Services, and the Agriculture Department. It's expected sometime in February and is aimed at developing plans to protect against bio-warfare, terrorism, and naturally occurring pandemics, and accidents involving the release of deadly bio-agents. It is expected to come up with recommendations for improving current biodefense capabilities as well as ways for the military and civilian agencies to work more effectively together.

The FY 2019 Budget: The Pentagon is busily putting together the first real budget under President Trump. The fiscal 2018 budget was a quick rewrite and modest increase over the Obama plan. It still did not pass Congress because it's caught up in the impasse over immigration reforms and the demand by Senate Democrats for parity in domestic spending.

But assuming Congress succeeds in lifting or eliminating budget caps, 2019 will bring the military closer to Trump's promised buildup. The request is more than just a spending plan. It also serves as a strategic document that indicates the Pentagon’s true priorities. This is where we find out how many troops, planes, and ships the Pentagon wants to fight current wars, and to be ready for future contingencies. The request is expected in February.

The National Military Strategy: In addition to the National Defense Strategy developed by the office of the Secretary of Defense, the chairman of the Joint Chiefs develops his own separate strategy document that focuses on developing war plans and the capabilities for carrying them out. There used to be a public version of the National Military Strategy, but in 2016, Chairman Gen. Joseph Dunford decided to keep it classified so as not to give away too much information to potential adversaries.