Israel is testing dirty nuclear bombs in its deserts which could be used in a "false flag" attack in the United States to implicate Iran, a former CIA and NSA contractor says.

“One has to wonder if they [Israelis] feel that the momentum for realizing ‘greater Israel’ is going away, and if the world opinion is shifting, which clearly it seems to be… [then] we have to be concerned with a false flag attack on the United States in order to justify a retaliatory strike against Iran,” said Steven D Kelley.

“We know that this Israel is actually testing dirty nuclear devices in their desert right now, and we know this has no strategic value other than to be used as a terrorist device in a false flag attack,” he added. “So this is a very dangerous time.”

Kelley made the remarks after Israel’s ambassador to the United States Ron Dermer called on Republicans in Congress to reject the nuclear accord.

During a meeting with House Republicans on Wednesday, Dermer said a nuclear accord with the Islamic Republic will pave the way for a powerful nuclear Iran. He said Congress is the last stop to thwart the agreement.

“The Israeli ambassador’s efforts to convince the American Republican members of Congress to reject this historic nuclear agreement between Iran and the P5+1 is continuation of the efforts by Israel to cast Iran as the enemy of the world, and the greatest source of terrorism, which of course we know [that's] exactly what Israel is,” Kelley stated.

“We know that AIPAC is going into overdrive trying to defeat this deal and convince Congress to hand a defeat to Obama. What should be noted now as we see the various voices that are coming out against this deal, we can trace these back to Israeli propaganda,” he added.

“And it should be very interesting now to see who those loudest voices are condemning this deal, because this is the best way to see who is the most deeply in the pocket of Israel and the Zionist lobby,” the analyst observed.

“But I still hope that this will work out, and that the efforts to defeat it will fail, and we can continue to move forward and defuse a very volatile situation, and God willing this will be successful,” Kelley concluded.

Iran and the P5+1 group -- the United States, Britain, France, China, Russia and Germany – reached a conclusion on the Joint Comprehensive Plan of Action (JCPOA) on July 14 in the Austrian capital of Vienna following days of intense talks over Tehran’s nuclear program.

Israeli Prime Minister Benjamin Netanyahu has fiercely opposed any nuclear agreement with Iran. He is pressing Washington to reject the nuclear agreement.