For the new U.S. Army budget (for the fiscal year starting in October 2018) there is money for upgrading 261 M1 tanks with the Israeli Trophy APS (Active Protection System). Trophy has already been tested on the M1 and Trophy has been around for a decade and has considerable combat experience. The U.S. has noted that Western tanks, like the M1 and Leopard 2 are vulnerable to these weapons. This was demonstrated recently in northwest Syria where Turkey lost at least ten Leopard 2s and older American M60s to Kornet ATGMs (Anti-Tank Guided Missile).
Israel has been a pioneer in APS development and there are several Israeli firms developing and selling APS gear. One of those firms created the Iron Fist APS, which lost out to Trophy, and all the money to be made equipping Israeli tanks with APS. In response the Iron Fist manufacturer (IMI), despite losing out in 2010 to Trophy (from Rafael), continued development without government funding. As a result Iron Fist developed into an APS that is lighter, more compact, easier to install and, on paper at least, has more features. Thus Iron Fist will be equipping lighter American armored vehicles like the M2. Iron Fist contains heat sensing as well as radar to detect threats and that includes rifle and machine-gun fire. These weapons cannot damage armored vehicles but it is useful for the crew to know where the fire is coming from. A full size Iron Fist can also jam guidance systems on some missiles and has a lower false-alarm rate. There is also a lightweight version with fewer of the extras but that can be put on much lighter vehicles like trucks. While Iron Fist has not been proven in combat like Trophy the manufacturer says it has worked well in tests and that was enough to encourage the American and Dutch armies to evaluate it on some of their armored vehicles. The Israeli army also selected Iron Fist for its Nemer heavy IFV (Infantry Fighting Vehicle).
The U.S. is also installing the Iron Curtain APS on Stryker armored vehicles. This APS comes from an American firm (Artis) which began development in 2005 and was part of a Department of Defense effort to catch up in APS development. Until now Trophy was the only APS most people heard about. In 2010 the first battalion of Merkavas was equipped with Trophy. Then in 2011 Trophy defeated incoming missiles and rockets in combat for the first time. This included ATGMs. This included modern Russian systems like the Kornet E. This is a laser guided missile with a range of 5,000 meters. The launcher has a thermal sight for use at night or in fog. The missile's warhead can penetrate enough modern tank armor to render the side armor of the Israeli Merkava tank vulnerable. The Kornet E missile weighs 8.2 kg (18 pounds) and the launcher 19 kg (42 pounds). A few weeks before the ATGM intercept Trophy defeated an RPG warhead (an unguided rocket propelled grenade fired from a metal tube balanced on the shoulder). As it was designed to do, Trophy operated automatically and the crew didn't realize the incoming RPG warhead or missile had been stopped until after it was over. That is how APS is supposed to work and Trophy has proved to be the most reliable and effective APS out there. By 2012 Israel was convinced sufficiently to equip all the Merkava tanks in an armor brigade with the Trophy APS. Now the U.S. army is equipping three brigades with Trophy.
This first combat use is a big deal because APS has been around for nearly three decades but demand and sales had been slow until then. The main purpose of APS is to stop ATGMs but on less heavily armored vehicles, stopping RPG type warheads is important as well. The Israeli Trophy APS uses better, more reliable, and more expensive technology than the original Russian Drozd (or its successors, like Arena) APS. This includes an electronic jammer that will defeat some types of ATGMs. For about $300,000 per system, Trophy will protect a vehicle from ATGMs as well as RPGs (which are much more common in combat zones). Israel is the first Western nation to have a lot of their tanks shot up by modern ATGMs and apparently fears the situation will only get worse. Trophy protected several Israeli tanks from ATGM and RPG attacks during the 50 Day War with Hamas in mid-2014.
In 2015 a lightweight (200 kg/440 pound) version of its Trophy APS called Trophy LV was introduced. This is intended for MRAPs (heavily armored trucks), IFVs (Infantry Fighting Vehicles) and other heavy vehicles that are lighter than tanks. The regular Trophy weighs about a ton and is one of several APS models on the market but it is also the one with the most impressive combat record. The Israeli manufacturer of Trophy also partners with American firms to manufacture Trophy and Trophy LV for the U.S. market. But in this case another Israeli firm entered the American market with the similar and more capable Iron First.
Israel first encountered ATGMs, on a large scale, in the 1973 Arab-Israeli war. But these were the clumsy, first generation missiles that turned out to be more smoke than fire. More recent ATGM designs have proved more reliable and effective but no nation, except Israel, has yet made a major commitment to APS. That may now change, simply because effective APS like Trophy are available and RPG and ATGM losses are growing.
Most APS consist of a radar to detect incoming missiles and small rockets to rush out and disable the incoming threat. A complete system weighs about a ton. There is also a Trophy Light (weighing half a ton) for lighter, often unarmored, vehicles and now the even lighter Trophy LV for vehicles as small as a hummer.
Russia pioneered the development of these anti-missile systems. The first one, the Drozd, entered active service in 1983, mainly for defense against American ATGMs. These the Russians feared a great deal, as American troops had a lot of them, and the Russians knew these missiles (like TOW) worked. Russia went on to improve their anti-missile systems but was never able to export many of them. This was largely because these systems were expensive (over $100,000 per vehicle), no one trusted Russian hi-tech that much and new tanks, like the American M-1, were seen as a bigger threat than ATGMs.