The U.S. spy satellite fleet is showing its age, and needs some new blood soon, before the older birds wear out. There are currently eight or nine American spy satellites working. The number is uncertain because they are launched, and taken out of service, in secrecy. It's possible that the ninth satellite is an advanced, and stealthy, version of the KH-11 photo satellite launched in 1999.
It is known that there are four KH-11s and four Lacrosse radar satellites up there. Half these birds have been up 10-15 years. This is longer than they were expected to last, so these are, in effect, living on borrowed time. Two others are 5-6 years old, and reaching the end of their 8 year design life. You can send up repair and refurbishment missions via the space shuttle, but that program is still stuck in review and recovery from the last accident.
The KH-11s and Lacrosse birds are the last of their kind, as a new generation of recon satellites are in the works. The older ones cost over a billion dollars each, and about half a billion dollars each to launch. The new ones will be smaller, cheaper (to build and launch), but nearly as capable as the 12-14 ton KH-11 birds. The trouble is, as new technology, these mini-sats will be subject to unexpected problems. Meanwhile, the NRO (National Reconnaissance Office) is under pressure to keep the costs down, and readiness up. That's a tough job when you are designing and deploying new technology.
Meanwhile, the subjects of all this space based spying are not cooperating either. During the Cold War, the Russians staged some large scale, and convincing, camouflage and deception operations for American spy satellites. China, and even Iran, have copied these techniques, apparently with the aid of Russian consultants. Thus while the U.S. can put a spy satellite over any spot in Iran every 2-3 hours, that provides enough "dead time" to implement deception measures.
It gets worse. An international array of "satellite hunters" keep an eye on American spy satellites, as well as anything else that can be seen up there with a half way decent backyard telescope. The KH-11 birds are big, and only 400 kilometers up. The smaller Lacrosse satellites are 650 kilometers from, and can still be seen from the earth. There are hundreds of these hobbyist satellite spotters, some of them very good, and they constantly share their latest findings via the Internet. It should come as no surprise that, lately, American spy satellites have orbits that take them over North Korea and Iran. The American satellites don't change orbit very often, as that uses up their limited amount of fuel. But when it does happen, the civilian satellite spotters are all over it. And that allows the people on the ground to set up their deceptions.
The new generation of smaller spy satellites will be more difficult to spot from the ground, returning some of the element of surprise to the satellite owner, and making deception more difficult. There will also be more of them. But that's the future. For now, there are only eight, or maybe nine.