A review recently commissioned by the German Parliament has determined that the country could legally finance the British or French nuclear weapons programs in exchange for their protection. The European Union could do the same if it changed its budgeting rules, the study found.

The German assessment comes after months of discussion in Berlin over whether Europe can still rely on American security assurances, which President Trump has called into question. Some have called for considering, as a replacement, a pan-European nuclear umbrella of existing French and British warheads.

The assessment provides a legal framework for such a plan. Britain or France, it finds, could legally base nuclear warheads on German soil.

The document states that “President Trump and his contradictory statements on NATO” have led to fears “that the U.S. could reduce its nuclear commitment” to Europe.