Problem is, we have signed on to a treaty not to allow space based weapons. So has Russia. Don't think China or India has, but it would only take a hand full of EMP bombs above North America to knock out the power grid as is and about 1/2 of all vehicles. Food would become short, especially in the inner cities, without adequate transportation. Grocery stores only have about a 3 day supply of food at any one time. Same with fuel deliveries to various stations. If trucks have electronics and they get knocked out. Also do trains have electronics? Most airplaces are EMP proof, as they can withstand a lightning strike. The reason for only about half the vehicles being knocked out is parking buildings, garages, and some if the engine is off might not burn out. I don't want to cut out most of the defence spending, but I am sure there is a LOT of fat.
I say cut all foreign aid, discresionary money, no welfare or aid for illegals. Require drug testing to get any type of federal aid, welfare, food stamps, even student loans. Talk about solving part of the drug problem. Raise the retirement age for people under 40 to 70. Stop taxing our manufacturers, and replace it with tarriffs on foreign goods. Get rid of the Education, Commerce, EPA. Allow drilling, pipelines, and mining on American soil and offshore. We need abundant cheap energy to keep the economy going. Alternatives will become available as time goes on, always has. Coal in the 1800's was replaced with oil in the 1900's. Eventually this will be replaced with hybrids, flywheels, solar, wind, and algae oil.
There are several ways to avoid an economic catistropic event.
Cut government spending.
Cut government regulation.
Cut certain taxes.
Grow the economy.
Go back to a gold standard with money.
Cut welfare spending, require welfare receipiants to go to a trade school or get an associate degree as long as they are on it.
Get independent of foreign energy.
Balance the trade deficit, of which half is in energy.
It will and may take a combination of all this to work.