Designed to penetrate deep into the earth... Did America resort to its most dangerous non-nuclear bombs in its strikes on Yemen?

On the night of October 17, the US Air Force deployed B-2 stealth bombers to launch large-scale strikes against five targets in Yemen using bunker-buster bombs.

The Military Watch magazine reported that the attack came after more than a year of exchange of attacks between the Yemeni Houthi group on the one hand, and the United States, the United Kingdom and Israel on the other, amid a consensus that the efforts led by the US Navy to cripple Yemeni combat capabilities were far from successful.

US Defense Secretary Lloyd Austin called the attack "unique evidence of the United States' ability to target facilities that our adversaries seek to keep out of our reach, no matter how deep underground or fortified they are."

While the Navy's Tomahawk cruise missiles and the missiles fired by F-18 fighters launched from aircraft carriers are not all that well-optimized for penetrating bunkers, the B-2 is considered the best-optimized asset in the Western world for such operations.

The use of the B-2 represents the culmination of nearly a decade of multinational efforts using Western weapons to neutralize Houthi weapons storage sites and key bases in Yemen.

The B-2's targets include three barracks areas and associated deep bunkers, each of which originally housed a Soviet Scud missile brigade from the 1980s, and in the 2000s were equipped with North Korean Hwasong-5/6 missiles.

The Houthi group has re-equipped itself with large numbers of unique ballistic missiles, believed to have been developed with Iranian and possibly North Korean support.

The most dangerous western bombs

Each B-2 can carry up to 40,000 pounds of munitions, and has an intercontinental range that allows it to strike targets globally from bases in Missouri and Guam.

However, the nature of the target of the recent attacks has raised widespread speculation that the bombers were equipped with GBU-57 Massive Ordnance Penetrator (MOP) bombs, which are too heavy for any other fighter aircraft to carry.

These bombs entered service in the early 2000s and are widely considered the most dangerous in NATO arsenals.

The GBU-57's ability to penetrate some of the best and most sensitive military sites around the world without crossing the nuclear threshold, thus giving the B-2 a particularly deep range, makes it without a doubt the most dangerous bomb in the Western world.

For deep fortifications, multiple GBU-57s may be necessary with their precise GPS guidance allowing bombers to place multiple warheads in a precise location, each one burrowing deeper than the previous one to achieve deeper penetration.

The bombs are expected to play a pivotal role in potential US strikes on Iran, which for decades has received extensive support from North Korea to fortify its military facilities, weapons depots and a number of its underground nuclear sites.

Serious defects

Military Watch magazine found that despite the power of the GBU-57 bombs, However, it has a number of serious flaws, the most important of which is that it can only be deployed by B-2 bombers, of which there are only 19 in service with the US Air Force.

The concentration of B-2 bombers at Whiteman Air Force Base makes them vulnerable to Chinese, Russian or North Korean attacks.

While the aircraft's exceptionally high maintenance requirements and low availability rates mean that only a very small number of bombers are typically available.

The B-2 was advanced when it was introduced in the late 1990s, although there were serious concerns in the West about the capabilities of advanced Soviet air defenses to threaten it, including at long ranges.

Advances in sensor technology leave stealth bombers of the 1990s with very limited ability to survive penetrating strikes.

Although a lighter, shorter-range successor to the B-2 is currently under development under the B-21 program, with the aircraft expected to take over the responsibility for deploying the GBU-57 , serious delays in the program mean the bombers will not be available until near the end of the decade.