Japan rejected a document calling for the “total elimination” of nuclear weapons despite being the only nation to have suffered atomic bombing.

Officials in Tokyo said the document’s wording could undermine Japan’s policy of reliance on the US nuclear umbrella for national security purposes.

The joint statement, which was presented on Wednesday at the second session of the Preparatory Committee for the 2015 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons in Geneva, urged all states to ban the use of nuclear weapons “under any circumstances”.

It stated that “the only way to guarantee that nuclear weapons will never be used again is through their total elimination”.

Signatories of the document had dropped the wording about making nuclear weapons illegal from the draft to persuade Japan to sign the joint statement. But other passages in the document led Japanese officials to hesitate about endorsing it, particularly the phrase, “It is in the interest of the very survival of humanity that nuclear weapons are never used again, under any circumstances”.

Even though Japan sought revisions for the phrasing, officials said it contradicts Japan’s nuclear deterrence policy. About 70 nations, including South Africa and Switzerland, have signed the document.

Chief Cabinet Secretary Yoshihide Suga defended Japan’s decision. “We decided not to give our approval after careful consideration over whether the wording was appropriate upon thinking about the difficult national security circumstances facing Japan,” he told a news conference in Tokyo.