(JTA) — Former Israeli prime minister Ehud Barak accused Benjamin Netanyahu of costing Israel $4.5 billion in defense aid because of Netanyahu’s tenuous relations with President Barack Obama.

Barak’s latest criticism on Israel’s prime minister came during an interview for Army Radio on Thursday, in which Barak quantified for the first time claims he made recently — including in an op-ed published Wednesday in the Washington Post — about the signing that day of a memorandum of understanding for $38 billion of US defense assistance to Israel over the coming 10 years.

“Had he handled it correctly, Netanyahu could have gotten another $4.5 billion,” Barak said.

The memorandum signed was on increasing assistance for Israel over the prior deal signed in 2007 under the George W. Bush administration, which guaranteed Israel $31 billion by 2017.

But Barak argued in the interview that the increase ”is only nominal,” and that in real terms aid has decreased because the package does not factor in rising arms prices.

“Israel will receive $3.8 billion a year — an important contribution to our security but far less than what could have been obtained before the prime minister chose to blatantly interfere with US politics,” Barak wrote in the Post op-ed.

“Expressing our opposition to the Iran nuclear deal was certainly legitimate,” said Barak. “But instead of holding a candid dialogue behind closed doors with President Obama, Netanyahu went behind his back to deliver a speech to Congress, shaking the foundations of bipartisan support for Israel and dividing Jewish opinion.”

In March 2015, Netanyahu delivered a speech before Congress at the invitation of then House Speaker John Boehner, a Republican, in which Netanyahu criticized the Obama Administration’s deal with Iran, offering the Islamic Republic sanctions relief in exchange to actions the White House said would prevent or slow down Iran’s ability to obtain or develop offensive nuclear capabilities.

The op-ed and Army Radio interview follow unspecified accusations by Barak that Netanyahu was “jeopardizing Israel’s security.” Israeli lawmakers on the left and the right urged Barak, a former chief of staff and defense minister with intimate knowledge of Israel’s security needs and establishment, to clarify these allegations.

A spokesperson for Netanyahu’s Likud party said the deal signed with the United States was “the best one obtainable.” It also labeled Barak “the most failed prime minister in Israel’s history,” adding that “he was kicked out after only a year but ion that time he managed to flee Lebanon and abandon soldiers.”