83 Republican and Democratic US Senators – representing 80% of the Senate- have sent a letter to President Obama, urging him to increase military aid package to Israel, given dramatically increased defence challenges in the region.

“In light of Israel’s dramatically rising defence challenges, we stand ready to support a substantially enhanced new long-term agreement to help provide Israel the resources it requires to defend itself and preserve its qualitative military edge,’’ said the letter, initiated by Republican Lindsey Graham and Democrat Chris Coons and which was signed by 51 Republican and 32 Democratic Senators.

The current memorandum of understanding between the United States and Israel details a defence package worth more than $2.9 billion (€2.6 billion), but is due to expire in 2017.

The two countries have been discussing a new ten-year agreement, but apparently gaps still exist on the financial extent of the deal and the military hardware it will include. During a visit to Israel last month, US Vice President Joe Biden warned that Israel would likely receive less that it had requested, while still ensuring Israeli security.

The Senators’letter listed a range of security threats facing Israel, including Hamas in the Gaza Strip, Hezbollah in Lebanon, ISIS-affiliates in the Egyptian Sinai Peninsula, and “the likelihood” that Iran will again attempt to develop a nuclear weapon.

The Senators said that Washington should “enhance its investment in the long-term security requirements of our closest Middle East ally.”

Senator Lindsey Graham vowed to “do everything I can to squeeze some money out of a tight budget to help increase funding for Israel.”

“Israel has to decide what to do and when to do it. But I can say this: we’ll have more money this year than potentially next year, because sequestration kicks back in,” he explained, referring to spending cuts the US federal government enacted in 2013.

A White House official said discussions with Israel were continuing.

"We are prepared to sign an MOU with Israel that would constitute the largest single pledge of military assistance to any country in US history," the official said.

The funding is intended to boost Israel's military and allow it to maintain a technological advantage over its Arab neighbors.

The letter said the Senate also intends to consider increased US funding for cooperative missile defense programs, similar to increases in the past several years.

In addition to military aid, the United States has worked in partnership with Israel to develop the country’s missile defence system, including the Iron Dome which successfully neutralized much of Hamas’ missile threat from Gaza during Operation Protective Edge in 2014, and the David's Sling medium- and long-range military defense system.