There's no indication yet whether classified documents on Israel's retaliation plans were leaked or hacked, White House national security spokesperson John Kirby told reporters Monday.

"I'm just not able to answer your question whether it was a leak or a hack at this point. We'll let the investigation pursue its logical course there," Kirby said.

Kirby said that President Joe Biden was "deeply concerned" about the incident, and that while they don't expect more documents to be revealed, they are on high alert amid the investigation.

"We're certainly going to keep our antenna up and our eyes open for any potential future disclosures," he said.

-ABC News' Cheyenne Haslett

Seven Israeli citizens were arrested after allegedly spying for Iran, Israeli authorities said Monday.

The Israel Security Agency and Israel Police said they "successfully dismantled a spy network" that allegedly gathered sensitive information on Israel Defense Forces bases and energy infrastructure.

The citizens were allegedly recruited by Iranian agents to conduct "security-related tasks" over at least two years, authorities said, including "extensive reconnaissance missions" on air force and navy installations, ports, Iron Dome system locations and energy infrastructure.

Photographs and videos of "numerous" IDF bases, ports and energy infrastructure were seized as part of the investigation, authorities said.

"It is assessed that these activities have inflicted security damage on the state," the ISA and Israel Police said.

The seven Israelis were allegedly paid hundreds of thousands of dollars, often through cryptocurrencies, for their work, authorities said.

Prosecutors are expected to file an indictment against them in the coming days.

U.S. Defense Secretary Lloyd Austin told reporters while traveling to Ukraine on Monday that it's "hard to say" what an Israeli retaliatory strike on Iran will look like, when asked whether the response should be proportional.

"That's an Israeli decision," he said. "Whether or not the Israelis believe [it] is proportional and [how] the Iranians perceive it, I mean, those are maybe two different things."

Austin told reporters that the U.S. is "going to continue to do everything we can" to get both parties to "begin to de-escalate."

-ABC News' Luis Martinez

Secretary of State Antony Blinken will begin a tour of Israel and other Middle Eastern nations on Monday in a bid to inject new life into stalled cease-fire and hostage release negotiations in Gaza, the State Department said.

Blinken "will discuss the importance of bringing the war in Gaza to an end, securing the release of all hostages and alleviating the suffering of the Palestinian people," the State Department notice said.

"He will continue discussions on post-conflict period planning and emphasize the need to chart a new path forward that enables Palestinians to rebuild their lives and realize their aspirations free from Hamas' tyranny," the statement said.

Blinken will also "underscore that additional food, medicine and other humanitarian aid must be delivered to civilians in Gaza," it continued.

The situation in Lebanon -- where Israel is continuing an intense air and ground campaign and Hezbollah is still firing across the shared border -- will also be a topic of discussion, the State Department said.

Blinken will continue pursuit of a "diplomatic resolution" that "allows civilians on both sides" of the border to return to their homes, the statement said.

-ABC News' Cindy Smith