>small in numbers
Bullshit.
There are more spies in the United States today than there were at the peak of the Cold War. However, many of them perform simple jobs, like passive espionage. For example, an African country rich in mineral resources might be interested in acquiring advanced mining technologies, so they send a few dozen "engineers" to work in mines of first world countries to study and observe. Obviously, that does not apply solely to mining, but also to IT, weapons manufacturing, construction, medicine, everything.
One worrying aspect of espionage is the sleeper cell factor. Speaking from the perspective of an American, there are thousands, maybe tens of thousands, of Chinese, Russia, Iranian and North Korean sleeper agents in the United States. And they are assigned some very shady missions. When given green light, they will demolish crucial infrastructure - dams, bridges, aqueducts, roads, the power grid, and so forth -, they will assassinate the entire presidential line of succession including most if not all Congressmen, plus several other key people in America like the director of the CIA, high ranking generals, governors etc, they will storm government buildings like the White House, the Federal Reserve Building, Congress, among others, and they will possibly want to destroy monuments and landmarks to destroy civilian morale. This all might sound crazy and unbelievable, but just think about it for a second. America has been taking Asian immigrants by the millions in the last two or so decades. One man, completely by himself, untrained and ill equipped, killed the President at the peak of the Cold War. And autistic virgin highschoolers can go on mass shootings and kill dozens. So what would many thousands of organized elite trained government agents equipped with state of the art classified equipment be able to do?
>weapons
It obviously depends on their mission. They will be unarmed in most cases, but suicide pills, knife pistols and explosive pens aren't unheard of in the strategic community.