The "Bunker Buster Act of 2025" aims to bolster Israel's defensive capabilities against a potential Iranian nuclear threat. Congress finds that Iran has significantly increased its uranium enrichment, possesses enough enriched uranium for multiple nuclear bombs, and continues to expand its nuclear program despite international censure. Furthermore, Iran supports proxy groups like Hamas, Houthis, and Hezbollah, which have launched numerous attacks against Israel and its allies. The bill authorizes the President, upon Israel's request and certification of vital U.S. national security interests, to undertake several key actions. These include providing for the construction of infrastructure in Israel to accommodate large ordnance systems designed to destroy underground nuclear facilities, such as extended runways for aircraft carrying the Massive Ordnance Penetrator (MOP) , along with the aircraft themselves, basing options, and munition storage facilities. A critical provision allows for the storage of MOPs or related munitions in Israel for U.S. use, with the possibility of transferring them to Israeli custody under specific conditions. These conditions require the President to certify that Iran is in noncompliance with the NPT Safeguards Agreement or has reduced IAEA inspector access, that such a transfer is vital to U.S. national security, and that Israel has no other means to achieve the objective of destroying Iran's underground nuclear infrastructure. Crucially, any transfer of MOPs to Israel would be subject to a dual-key control system , requiring explicit approval from the U.S. President for deployment. The bill also authorizes training for Israeli personnel on these munitions and joint research and development to enhance U.S. ordnance and develop Israeli capabilities for destroying underground infrastructure, including Hezbollah rocket facilities and Iranian nuclear sites. The legislation explicitly clarifies that it does not authorize the use of military force against Iran.