The Patton may reliably soldier on and contribute its heavy firepower to the battlefield—but in an era where minimizing casualties and denying propaganda victories to the other side is important, its dated armor protection will remain a liability.

Just how far can you soup up a tank from the 1960s?

(This first appeared serveral years ago.)

The M60 Patton was the mainstay of the U.S tank fleet in the 1960s and 1970s, before being replaced by the M1 Abrams tank currently in service. However, more than five thousand Pattons remain in service in the armies of nineteen countries. Earlier this year, Raytheon unveiled its Service-Life Extension Package (SLEP) upgrade featuring a new engine, fire control system and 120-millimeter gun.

This M60 SLEP is in competition with a pre-existing three-tier upgrade offered by Israel Military Industries for their M60 Sabra. Sabras in Turkish service, designated the M60T, are active on the battlefield of Northern Syria today, while older-model Pattons are fighting on both sides of the war in Yemen.

The new Pattons are faster and deadlier—but are they tough enough for the modern battlefield?

America’s Cold War Battle Tank

The M60 traces its ancestry all the way back to the M26 Pershing heavy tank, a few dozen of which saw action at the end of the World War II. The Pershing was evolved into a series of Patton tanks armed with 90mm guns, including the M46, M47 and M48. The M60, introduced in 1960, was the last: a tall-profiled brawler designed to outmatch the ubiquitous Soviet T-54 tank by virtue of its heavier armor and long M68 105 millimeter gun.

The 50-ton M60s were deployed to Europe in case World War III broke out, and didn’t see action in the Vietnam War, except for some bridge-laying and engineering variants. Instead, M48 tanks took on North Vietnamese PT-76s and T-54s in a small number of engagements, and even battled Swedish-made tanks in the Dominican Republic.

It was in the Middle East that the M60 Patton first showed its mettle. During the Yom Kippur War, Israeli M60s rumbled to the rescue of the Seventh and 188th Armored Brigades on the Golan Heights, breaking the back of a Syrian onslaught numbering over 3 thousand tanks. However, on the southern front, AT-3 anti-tank missiles devastated M60s counterattacking the Egyptian beachhead on the Suez canal. The Patton’s tall profile made it an easy target, while its frontally mounted hydraulics were prone to bursting into flames when the armor was penetrated. Nonetheless, the Israelis were so fond of the Patton that they kept it in service until 2014, upgrading them into several generations of Mag’ach tanks.

The Patton saw quite a few upgrades over its service life. The avant-garde M60A2 “Starship” variant used a 155-millimeter gun that could fire Shillelagh anti-tank missiles; it was quickly phased out because of crippling technical limitations. The final version, the M60A3 TTS, came with improved fire control systems and thermal sights that made it an effective night fighter. Some Marine Corps Pattons were even fitted with explosive-reactive armor.

However, by the 1980s the Soviet Union had exported large numbers of the T-72 tank, which equaled or outmatched the Patton in armor and firepower. Meanwhile, the United States introduced the M1 Abrams tank, which proved a decisive technological leap ahead in both firepower (once it received a 120 millimeter gun) and protection, thanks to its composite armor.

The last U.S. M60s were operated by the Marine Corps, and finally saw heavy combat in the 1991 Gulf War in Kuwait, knocking out around 100 Iraqi tanks for the loss of a single Patton. However, that reflected the unequal training and tactics of the opposing sides more than anything else, and shortly afterwards the Patton was phased out of U.S. service.

However, M60s remain the most numerous main battle tank in service in many countries today, including Egypt (1,700), Turkey (932), Taiwan (450), Saudi Arabia (450), Morocco (427), Thailand (178), and Bahrain (180.)

What’s Improved in the SLEP and Sabra M60s?

Raytheon’s SLEP upgrade focuses on improved firepower and mobility.

First, it replaces the old M68 gun with the potent 120mm M256 gun used in the Abrams tank. This will transform the Patton from a tank that would struggle against a 1980s era T-72 to one that can penetrate most modern tanks. Furthermore, so as to actually hit the target, the M60 SLEP has a new digital targeting system taken from the M1A1D to replace the Patton’s dated technology. Modern targeting computers have made tank gunnery while moving viable, so this is a big plus. Finally, the hydraulic system for rotating the turret has been replaced with an electric one, increasing rotation speed and reducing the aforementioned “bursting into flames” problem when hit.

Second, Raytheon has replaced the 750 horsepower diesel engine with a brand new 950 horsepower motor. This is nice, because the basic M60 lumbers at 30 miles per hour, while maximum speeds over 40 miles per hour are typical for modern Western tanks.

Now, the prototype filmed in Raytheon’s promo video also has a lot of features they don’t advertise: slat armor, which can be effective at deflecting shaped charge warheads in rocket propelled grenades, add-on armor panels, and an auxiliary power unit and cooling fans in the back. It appears that these are not standard features of the SLEP upgrade.

For comparison, the Israeli Sabra II upgrade also boasts a 120 millimeter gun of comparable performance paired with a new targeting computer, as well as a superior 1 thousand horsepower engine which increases speed to 34 miles per hour. Unlike the SLEP, the Sabra also has beefed up armor, giving the turret an angular shape. This includes the addition of explosive-reactive armor—that is, bricks of explosive that prematurely detonate incoming missiles and shells –as well as appliqué armor plates.

A similar Mag’ach 7C tank fitted with appliqué armor reportedly survived eighteen hits from Hezbollah AT-3 Sagger missiles without being penetrated. However, the Sagger dates back to the 1960s and current missiles have far greater penetrating power.

How Useful Are Those Upgrades?

The more powerful engines will help the Patton keep up with other mechanized units on the battlefield. However, even with the upgrade, the M60’s power-to-weight ratio isn’t stellar.

With the 120-millimeter gun and new fire control system, the M60 can both hit and destroy the majority of tanks in use today at medium to long range. M60 operators will likely lack the advanced M829E3 and E4 depleted uranium rounds designed to circumvent the most sophisticated reactive armor systems, but few operational tanks benefit from them so far. So, the M60 SLEP could be a decent tank hunter.

However, the majority of tanks on the battlefield these days aren’t fighting other tanks. They’re exchanging fire with insurgent infantry—increasing numbers of whom are packing modern long-range anti-tank guided missiles like the Kornet, as well as more widespread short-range rocket propelled grenades. The best of these weapons have proven effective even against modern tanks such as the M1 and Merkava.

The Patton is considerably more vulnerable than the M1 or Merkava—and even the older T-72! The Patton’s old-fashioned cast steel frontal armor is rated equivalent to 253 millimeters Rolled Hardened Armor, the standard measure of tank armor effectiveness. Modern tanks use composite armor which is drastically more effective for the same weight, especially against shaped charge warheads. A modern M1A2 is rated equivalent to around 800 millimeters verses tanks shells and 1300 verses shaped charges.

By contrast, 90s-era 120 millimeter sabot shells could pierce the equivalent of around 700 RHA, and the AT-17 Kornet anti-tank missile can penetrate 1300 millimeters.

The Patton is also easier to hit because of its tall profile, and more likely to burst into flames when penetrated because the main gun ammunition is not stowed separately, as it is in the Abrams.

The M60 SLEP doesn’t feature improved armor. The upgraded Sabra does—and we know already how the up-armored Pattons have fared against anti-tank guided missiles thanks to Turkey.

On April 21 of this year, a Turkish M60T in Bashiqueh, Iraq, was struck by an ISIS tandem-charge Kornet anti-tank missile, damaging the vehicle but not harming the crew. However, the tank appears to have been put out of operation.

In August this year, Turkish M60A3 and M60T poured over the border in support of allied rebels as part of Operation Euphrates Shield, first chasing ISIS out of the town of Jarablus without a fight and then attacking Kurdish militias. Kurdish fighters knocked out several M60s with long-range missiles, inflicting the first Turkish casualties in the intervention.

Turkish M60T Sabra tanks eventually redirected their firepower against ISIS-held towns—and unfortunately, were subject to a series of successful attacks by Kornet missiles. In the videos posted online, two of the three Pattons destroyed burst into flames.

In the second incident, only one of the crew survived. By now it is believed at least eleven Turkish Pattons have been destroyed in Syria.

The situation is even worse in Yemen, where Pattons are operated both by Army units supporting Houthi rebels as well as Saudi Arabia. More than 22 destroyed Patton’s have been recorded in the conflict.