Sen. Marco Rubio said Sunday that whoever leaked classified U.S. documents assessing Israeli military plans likely committed treason and should be prosecuted.

Appearing on “Fox News Sunday,” the Florida Republican said that this month’s leak of sensitive American military assessments directly harmed both Israel and the U.S.

Mr. Rubio also said the incident is further proof of an anti-Israel contingent inside the U.S. government that sympathizes with Iran and its allies.

“There are elements within our U.S. government that hate Israel, that sympathize with Hamas and Hezbollah, and this looks to me … that this was a treasonous act by someone in the U.S. government to undermine Israel and by extension, the national security of the United States,” he said.

Mr. Rubio added that the leak was “done deliberately to harm Israel.”

“And it’s treason, and it should be prosecuted as such,” said Mr. Rubio, the top Republican on the Senate Select Committee on Intelligence.

As a high crime, treason can carry the death penalty.

The leaked documents were attributed to the National Geospatial-Intelligence Agency and the National Security Agency, and were posted to the Telegram messaging app earlier this month.

The materials appeared to be internal U.S. assessments of Israel’s plans for military strikes against Iran. Israel carried out those strikes over the weekend, hitting several Iranian military sites in retaliation for Iran’s Oct. 1 ballistic missile attack against Israel.

Israel reportedly had to delay its attack on Iran because of the leak. The FBI is investigating the incident.