Left-wing Democratic lawmakers have called on the United States to break its silence on Israel’s suspected nuclear weapons program, shattering a decades-long bipartisan reticence in Washington on the sensitive issue, AFP reports.

Israel is widely believed to have developed nuclear weapons in the 1960s but keeps a deliberately ambiguous policy by neither confirming nor denying its arsenal, which is not subject to any international monitoring.

Some 30 Democratic lawmakers, led by Representative Joaquin Castro, said that the United States needed clear answers after President Donald Trump joined Israel in a war against Iran, launched in part over charges that Tehran has been seeking to build a weapon through its nominally civilian nuclear program.

“We cannot develop [a] coherent nonproliferation policy for the Middle East, including with respect to Iran’s civil nuclear program and Saudi Arabia’s civil nuclear ambitions, while maintaining a policy of official silence about the nuclear weapons capabilities of one party central to the ongoing conflict in which the United States is a direct participant,” they have written in a letter, made public late on Wednesday.

“We ask that you hold Israel to the same standard of transparency that the United States expects from any other country that may be pursuing or retaining nuclear weapons capability.”

The lawmakers have asked Secretary of State Marco Rubio to reply by May 18 to explain Israel’s nuclear capabilities as well as its nuclear doctrine, including whether Israel could use the ultra-destructive weapons in Iran.