President Obama on Monday signed a emergency defense package providing an additional $225 million in funding for the Iron Dome program, a missile defense system that has helped shield Israel from Palestinian rocket fire.

The defense system has proven highly effective — intercepting as many as nine in 10 Hamas rockets, according to Israeli officials — and helped limit civilian casualties during the latest round of fighting in the region.

"The United States is proud that the Iron Dome system developed in coordination with Israel and funded by the United States has saved countless Israeli lives," White House press secretary Josh Earnest said in a statement. "Continued bipartisan support for Iron Dome funding ensures Israel will retain vital defense against rockets and artillery in light of the enduring threats."

The funding comes on top of some $700 million the U.S. has already provided Israel to fund the radar-guided defense system.

Only still photographers were allowed into the Oval Office for the signing ceremony and the president did not make any comments. The limited pageantry fueled some speculation that the White House remained upset with Israel over its bombing of a United Nations refugee site in Gaza over the weekend.

Senior Obama adviser Valerie Jarrett called the shelling "indefensible" and State Department spokeswoman Jen Psaki labeled it "disgraceful," the strongest condemnation of Israeli actions to date.

Earnest said that while the "United States supports Israel’s right to defend itself" against rocket attacks, the White House also called "on Israeli authorities to take all feasible precautions to prevent civilian casualties in Gaza and protect the civilian Palestinian population from the effects of attacks, and we continue to stress that all parties to the conflict must comply with international humanitarian law."

Earlier Monday, Israel and Hamas announced they had agreed to a 72-hour ceasefire agreement with hopes negotiators could strike a longer-term agreement while meeting in Cairo. More than 1,800 Palestinians and 67 Israelis have died in the fighting.