Intelligence compromises over the past five years, including the transfer of top-secret data on Hillary Clinton’s private email server, inflicted serious damage on U.S. national security, the chairman of the House Armed Services Committee said Wednesday.

Rep. Mac Thornberry (R., Tex.), who has headed the committee since January, said the combined effect of disclosures to the anti-secrecy website Wikileaks, the theft of over a million National Security Agency secret documents by the renegade NSA contractor Edward Snowden, and now the potential loss of secrets from Clinton’s use of a private email system is helping American adversaries such as China, Russia, and the Islamic State.

"It has certainly helped our primary adversaries," Thornberry said during a wide-ranging interview in his office at the Rayburn building.

The chairman said he believes the compromise of intelligence information over the past five years is "probably the most damaging thing that’s happened to U.S. national security."

"Whether it was Wikileaks or Snowden or now the Hillary emails, we have done more to hurt ourselves than the Russians, the Chinese, the terrorists, or anybody else that you want to name."

"This is serious business when you have top secret emails on a private server, and then you think it all goes away by saying ‘I’m sorry.’ It’s just… The damage to the country is just enormous when you put these compromises together."

In the interview, Thornberry also said Congress is close to finishing work on a House-Senate conference on the fiscal 2016 defense authorization bill that will provide some relief for Pentagon budget woes by allowing the use of funds slated for overseas operations.

The White House has threatened to veto the bill over the provisions, though the legislation funds the president’s budget request of $561 billion.

On other issues, Thornberry said:

• Legislation is being considered that would partially undo Budget Control Act limits on spending in ways that will not increase the federal deficit.

• The Iran nuclear deal lacks adequate verification provisions and will not resolve issues of past nuclear arms work. Also, the president’s assertion that rejecting the Iran nuclear deal would lead to war is a "straw man" argument meant to defend a bad agreement. The agreement "strengthens" the Islamist regime in Tehran and makes Iran less likely to moderate its behavior over the next 15 years.

"The president made a fundamental miscalculation" about Iran’s future, he said, noting that Iran’s Quds forces will be strengthened by the pact and the release of billions in frozen funds.

• Congress will be briefed this week on Iran’s continuing covert support to terrorists and insurgents in Yemen, Lebanon, and Afghanistan, as well as on Iran’s missile programs, which will be "unconstrained completely" after embargoed funds are released.

• The administration will undermine significant gains made by the U.S. military against insurgents in Afghanistan by pulling out all U.S. troops. At least 10,000 troops should remain to support Afghan security forces as they are strengthened.

• Terrorism is resurgent in Afghanistan as the Islamic State (IS, also known as ISIS or ISIL) grows, and the Taliban is becoming more violent as a result of a split within its ranks.

• The U.S. military has been severely restricted in the current bombing campaign in Syria and Iraq, raising questions about the administration’s stated commitment to destroy and degrade IS.

"It raises questions about whether the United States is serious about degrading ISIS," Thornberry said.

• Russia’s nuclear and conventional military buildup, as well as China’s modernization and Iran’s nuclear ambitions, should lead to a major reassessment of U.S. nuclear strategy and a reinvigoration of strategic nuclear modernization.

"[Russia’s] economy may be in trouble but they are making key investments in a number of weapons systems that cause us a lot of problems. And the Chinese are as well."

• The Pentagon has become "alarmed" at some of China’s advanced military capabilities that appear designed for use in a conflict with the United States and to prevent the American military from operating in the Pacific.

On the damage caused by intelligence compromises, the Russian and Chinese governments and Islamic terrorists benefitted from NSA leaks, Thornberry said.

"The terrorists adapted their tactics with all the Snowden leaks," he said. "They saw what we do, and how we do it and changed accordingly."

Thornberry also said that Russia and China were "informed" by the NSA disclosures. He did not elaborate.

"And so we are helping our adversaries and hurting ourselves by not being as careful as we should have been with this information."

Former NSA Deputy Director Chris Inglis and former NSA Director Michael Hayden told the Washington Times last year that the Islamic State learned from leaked NSA documents how to avoid NSA surveillance.

The Clinton email scandal surfaced last month when the U.S. intelligence community inspector general disclosed that top-secret information was placed on Clinton’s private email server that she used while serving as secretary of state.

The top-secret classified data included intelligence information derived from satellites and electronic communications.

Clinton at first denied any classified information was stored on some 60,000 emails on the private server. Later she revised her stance to say that no "marked" classified information was contained in the emails.

This week the Democratic presidential contender said she was sorry for using the server. The apology followed a second U.S. government security review that uncovered additional classified data.

Clinton aides have sought to downplay the security compromises by asserting that it involves a dispute over classification between the State Department and intelligence agencies.

The FBI is investigating the compromise of top-secret information that was discovered last month in a sample of some 60,000 emails exchanged by Clinton and her aides while she was secretary of state from 2009 to 2013.

About 30,000 emails were provided to the FBI and investigators are attempting to recover an estimated 32,000 emails that Clinton said were "personal" and unrelated to her work.

Earlier damaging intelligence breaches included the electronic theft of hundreds of thousands of classified military and diplomatic documents by Army Sgt. Bradley Manning that were given to Wikileaks in 2010. Manning was convicted of espionage, theft, and fraud in July 2013 and is serving a 35-year prison term.

Months later, Snowden, who has said that he believes the NSA is conspiring to usurp American democracy through illicit electronic surveillance, used his access to top-secret documents while working as an NSA computer administrator to download an estimated 1.7 million classified documents. Those documents were provided to several journalists.

Snowden fled to Hong Kong and later Russia, where he is currently under Russian government protection. He faces prosecution from the Justice Department in America.

Thornberry declined to say which Republican presidential candidate he will support.

"There is a big field," he said. "I am most interested in who is going to be the best commander-in-chief to clean up the mess that’s going to be left on his or her desk on day one. I don’t know who that is but that’s sure what I’m listening for."