Israel-Gaza live updates: Israel 'deepening the war' in Gaza: Netanyahu

As the death toll in Gaza nears 20,000, National Security Council spokesman John Kirby said Wednesday that "the right number of civilian casualties is zero."

“There's no number of an innocent civilian killed or wounded that's acceptable, nor should it be acceptable by anybody, which is why we're going to continue to work with the Israelis about being more precise, more targeted, more delivered in their military operations," Kirby said.

He said Israel has “taken on our concerns, and they have been receptive, and they have adapted their military operations to try to bring the number of civilian casualties down.”

“We want to see the number zero, but they have made some efforts,” Kirby added.

-ABC News’ Karen Travers and Cheyenne Haslett

The Palestinian Islamic Jihad released a video on Tuesday of two Israeli hostages pleading for their release.

The men -- who identified themselves as Gadi Moses and Elad Katzir -- spoke as they appeared in front of a plain background in the nearly 2 1/2-minute video.

"I want to convey to my friends and supporters that we must increase the pressure so that the government understands what we want," Moses said in the video provided by the hostage-takers. "We want every effort to be made so that we will soon arrive back home to our friends, our family, to our home."

Addressing Israeli leaders, including Prime Minister Benjamin Netanyahu and Israel Defense Forces Commander Hertzi Halevi, Moses said he feared being killed by an Israeli bomb.

"This situation where we could die at any moment is an unbearable situation; there is a reasonable chance that we will also be killed tonight," he said.

Katzir, 47, also said the bombings "endanger our lives" and urged Israeli leaders to make a prisoner exchange deal.

"We don't want to die in Gaza," he said. "We want them to do whatever it takes to bring us home."

It is unclear when the video was recorded and if the men were told what to say.

The hostages' families gave ABC News permission to use stills from the video.

The Israel Defense Forces said it’s found about 1,500 tunnel shafts and underground passages in Gaza since the start of the war.

The IDF -- which has consistently accused Hamas of using civilians in Gaza as human shields -- said most tunnels were under schools, hospitals, mosques, United Nations facilities and civilian institutions.

-ABC News’ Dana Savir

Forty trucks carrying commercial goods crossed into the Gaza Strip on Tuesday -- the first time commercial goods entered since the war began, Palestinian border crossing spokesman Wael Abu Omar told ABC News.

The trucks -- carrying items including flour, oil and salt -- entered through Israel’s Kerem Shalom crossing, the spokesman said.

-ABC News’ Ayat Al-Tawy