What happens when you pull out of nuclear arms agreements with hostile foreign countries and test missiles that were previously BANNED? Aren't you inviting resumption of a nuclear arms race with the inevitable result of war? Why else eliminate the brakes unless you want the bomb-loaded car going down the hill to accelerate and keep going until?
Rosie, you are asking two separate questions there!
Environmental protection laws are established for very good reasons, and even the People's Republic of China has recognised the problems its massive industrial developments have caused, and is now working hard to put that right.
There is a point many people may not realise. Forget trade agreements or wars, tariffs, etc.
A lot of nations and blocs like the EU have long imposed certain minimum standards equally on both internally made and imported goods, to ensure at least equivalence to the importing nation's. These are mainly for safety and quality (often linked). In the EU, the outwards sign is the "CE" mark on a product, and sometimes a leaflet listing the relevant detail standards. The US equivalent is the ANSI (American National Standards Institute) but whatever happens, the exported goods must meet the importers' legal specifications.
More recently though, standards have started to spread possibly to employment-protection and certainly to environmental responsibility demonstrated by the producers. Some are national or bloc in origin, but most reflect agreements by the International Standards Organisation, to which almost every country in the world is either a full or "reader" member. The USA and EU members are all full ISO members.
The ISO instituted a management-control system called ISO900x (x is a digit from 0 upwards), some decades now - based on a British military equipment-guarantee scheme called DEF-STAN[number]. More recently ISO created an environmental responsibility system called ISO1400x. Such schemes rely on certified companies maintaining full traceability and recording of the detail technical systems involved; and are costly and difficult to obtain and maintain.
I do not know if ISO has any similar scheme for standards of employee rights and welfare, but this too may be a growing factor in international trade: humanity apart, reputable firms do not want the bad publicity of association with "sweat-shops", for example.
National law may not insist on ISO or EU accreditation, but many customers including governmental organisations, do. Although a manufacturer can obtain them anyway, if its home country lacks the legal and administrative support it will be much more difficult to do so, because accreditation needs independent assessors as well as the laws as a guide. Particularly, ISO14000 requires such actions as proving continual monitoring fuel and electricity consumption, and ensuring waste materials are disposed of properly via known, legal and reputable services.
So if a manufacturer cannot show keeping to the relevant standards, it will deter potential customers. If its own country has no legal and administrative support for companies needing that accreditation, it will find it very difficult to gain accreditation in the first place.
Therefore, by dismantling laws protecting the environment, employee welfare etc., the USA could damage its own ability to export goods. And no-one will accept it bleating about importers being "protectionist", if obeying laws or standards ultimately from the same ISO to which both parties are full members!
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On your other question, both the USA and Russian Federation seem to be embarking on a new arms race based on developing a new breed of cruise (steered rather than ballistic) missiles that may or may not carry nuclear war-heads, but are too fast for existing defence systems to track and shoot down.
It's all a very frightening prospect...
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[Edited to correct and shorten slightly.]
Durdle 