America signed an agreement yesterday to increase its annual military aid to Israel by 25%, providing $30 billion over the next decade to assure Israel’s edge over other armed forces in the Middle East.

The American undersecretary of state for political affairs, Nicholas Burns, and the director-general of the Israeli Foreign Ministry, Aharon Abramovich, signed the memorandum of understanding during a ceremony in Jerusalem with the governor of the Bank of Israel, Stanley Fischer, who negotiated the accord. President Bush and Prime Minister Olmert settled on the increase during a White House meeting in June.

“We look at this region and we see that a secure and strong Israel is in the interest of the United States,” Mr. Burns said.

Secretary of State Rice presented the aid boost during a visit last month as part of a regional package that includes $20 billion in weapons sales for Saudi Arabia and $13 billion in assistance for Egypt. She said the money was meant to counter threats from Iran and Syria, as well as possible terrorist attacks from Lebanon’s Shiite Muslim Hezbollah group and Al Qaeda.

The agreement lets Israel use 26% of the aid money to buy equipment from Israeli defense contractors, such as state-owned Israel Aerospace Industries Ltd. and Elbit Systems Ltd. The rest must go to American companies. Israel is scheduled to receive the first payment of $2.6 billion in October 2008, with the package growing each year by about $150 million until it reaches an annual $3.1 billion in 2011, Mr. Burns said.

The aid package “illustrates the depth of the relationship between the two countries and the commitment of the United States to the defense of Israel and preserving its qualitative superiority,” Mr. Olmert said in a statement sent by e-mail.