The United States may be preparing to strike Iran’s nuclear program. The largest weapon Israel could deliver is the 5,000 pound GBU-28, this would involve their entire F-15I fleet, tanker logistics, permission for transit or sneaking along the Iraqi-Jordanian border.
The 30,000 pound GBU-57A/B Massive Ordnance Penetrator requires a large bomber to carry it - either the B-52 for undefended targets, or the B-2 Spirit for places with significant air defenses. This was developed in part as a counter to the temptation to use the B61-12 dial a yield nuke for hardened targets.
The studies I have read on Israeli strike plans indicate that the Iranians built with the expectation the GBU-28 would be the biggest thing thrown at them. The MOP invalidates such construction world wide.
This might just be an effort to force the Iranian government to take some crappy replacement to the JCPOA, but given that we’ve got SecDef Juicebox, who knows what dumb ideas are being discussed via Signal …
The GBU-57A/B most likely doesn’t have a significant range after release, forcing the B-2 bomber to approach relatively close to the target area, which poses a risk.
I wouldn’t be surprised if low-yield nuclear weapons were used instead.