James Mattis, Donald Trump’s choice for Defense secretary, advocated several shifts in U.S. national security policy in his confirmation hearing Thursday, including a much tougher stance on Russia than the president-elect has articulated.

On several topics during his Senate Armed Services testimony, the retired Marine Corps four-star general differed in substance or tone from positions Trump took in the campaign. Unless Trump or Mattis changes his view, the contrasts could lead to tensions between the White House and the Pentagon.

Sen. Elizabeth Warren, D-Mass., a new member of the committee, told Mattis that U.S. national security may depend on his willingness to push back within the Trump administration on Russia and other issues.

“We are counting on you,” Warren told the 66-year old, who commanded U.S. troops in the Middle East before retiring from the military in 2013.

After the hearing, the committee approved, 24-3, a measure that would exempt Mattis from a statute requiring that an officer be retired at least seven years before he or she can serve as Defense secretary. Warren voted against the waiver, as did fellow Democrats Kirsten Gillibrand of New York and Richard Blumenthal of Connecticut. Just hours later, the Senate approved the waiver, 81-17.

Across the Capitol, the House Armed Services Committee will vote Thursday afternoon on its version of the waiver, but key Democrats are urging their colleagues to object amid concerns that Mattis has not testified before lawmakers in that chamber. The House is expected to on the waiver on Friday.

Senate Republicans expect a confirmation vote on Inauguration Day.

Sabers rattle on Russia

During his testimony before the Senate Armed Services panel, Mattis named Russia the top threat to U.S. security. “Russia is raising grave concerns on several fronts,” he said, adding that there are “an increasing number of areas where we are going to have to confront Russia.”

At one point, Mattis said, Trump, who has praised Russian President Vladimir Putin, asked him in a private meeting “why I felt so strongly” about Russia.

Mattis told the committee that Putin “is trying to break” western allies. Because of Russia, China and terrorism, Mattis warned the international order “is under the biggest attack since World War II.”

Armed Services Chairman John McCain, R-Ariz., was characteristically blunt about Russia, saying Putin “wants to be our enemy. He needs us as his enemy.”

Under questioning from McCain, Mattis agreed that U.S. troops should be stationed permanently in the Baltics. Mattis also endorsed continued spending on the European Deterrence Initiative, a multibillion dollar U.S. project to bolster allied forces on Russia’s western flank, and to generally make NATO partners a centerpiece of his policies.

Mattis also said he might consider a “more aggressive timeline” for destroying the Islamic State’s hub in Raqqaa, Syria, a move that would be complicated by Russia’s military engagement in that country.

And Mattis said America must communicate clearly to adversaries in cyberspace which actions would trigger what U.S. responses — an issue that clearly involves Russia.

Other disparities with Trump

Regarding other threats, Mattis took positions in his verbal testimony that would not represent new U.S. policies but would still be at odds with Trump’s previous statements — and sometimes at odds with the general’s own past utterances.

Mattis, for example, said the United States must continue to adhere to the Iran nuclear agreement, marking a clear departure from the president-elect.

Mattis said he has no intention of rolling back the Pentagon policy permitting women to compete for any job in the military, including certain combat roles that have previously been off-limits — this despite his previous skepticism about the change.

The general also indicated he has no intention to alter the integration of LGBT people in the armed services.

“Frankly, senator, I’ve never cared much about two consenting adults and who they go to bed with,” Mattis said to Sen. Mazie K. Hirono, D-Hawaii.

While Trump has espoused killing the families of terrorists, if necessary, Mattis wrote in a 56-page questionnaire: “The killing of non-combatants in a war against a non-state enemy violates Common Article 3 the Geneva Conventions. Legal questions aside, it is my view that such actions would be self-defeating and a betrayal of our ideals.”

Likewise, while Trump has endorsed brutal interrogation of detainees using methods that many consider torture, Mattis wrote that he fully supports the more limited interrogation methods spelled out in the Army’s field manual on the subject as “the single standard for all military interrogations.”

On Russia, he wrote: “Challenges posed by Russia include alarming messages from Moscow regarding the use of nuclear weapons; treaty violations; the use of hybrid warfare tactics to destabilize other countries; and involvement in hacking and information warfare.”

Trump also suggested during the campaign that the United States should consider withdrawing its military umbrella from Japan and South Korea unless they, too, pay more for their defense, even though they currently allocate the equivalent of billions of dollars for that purpose.

The committee asked Mattis: “Do you believe the United States should withdraw forces from Japan and South Korea if those allies do not provide substantial additional support on top of the existing cost sharing arrangements in both countries?”

Mattis took a pass on answering directly. “I believe the United States is stronger when we uphold our treaty obligations, and when we stand by our allies and partners,” he wrote. “We expect our allies and partners to uphold their obligations as well. If confirmed, I will consult with the Chairman of the Joint Chiefs and I will provide my best professional advice on any such proposals to the President.”

Notable positions

Based on his hearing and written statements for the committee, Mattis’ other noteworthy positions include:

• Support for modernizing all three legs of the nuclear triad — air-, ground- and sea-launched weapons — despite previous statements raising questions about the continued need for ground-based missiles. He withheld judgment on a proposed new air-launched, nuclear-tipped cruise missile.

• Backing for “offensive space control” capabilities — or systems that can wage war to defend U.S. satellites.

• Acknowledgement that deterrence is failing in cyberspace and that Chinese theft of U.S. intellectual property, in particular, is a significant security threat.

• Support for building a 350-ship Navy, but an unwillingness to commit to some other goals, notably Trump’s stated end-strength objectives. Unlike aircraft manufacturers, Navy shipbuilders have so far eluded Trump’s Twitter barbs about contract costs.

• Backing for continued use of “unfunded priorities lists,” the services’ statements of spending priorities that did not meet the budget.

• Opposition to insisting that non-defense programs get budget increases equal to defense.

• Withholding a position on the need for a new round of military base closures.