Washington (CNN) Rex Tillerson, the retired ExxonMobil CEO who President-elect Donald Trump nominated to be secretary of state, was something of an unknown before his Senate confirmation hearing Wednesday.

But after about eight hours of testimony, there was more clarity on some -- but not all -- of Tillerson's views:

Russia

"Russia today poses a danger, but it is not unpredictable in advancing its own interests ... I think the important conversation that we have to have with them is, does Russia want to now and forever be an adversary of the United States? We're not likely to ever be friends."

Nuclear proliferation

"We simply cannot back away from our commitment" to reduce nuclear weapons.

Trump tweeting

"I don't think I will be telling the boss how he ought to communicate the American people. That's going to be his choice ... It would be my expectation that any way the president might choose to communicate through whatever method would be supportive of that policy we both agreed on."

Climate change

"The risk of climate change does exist and the consequences of it could be serious enough that actions should be taken ... I don't see it as the imminent national security threat that perhaps others do."

The Iran nuclear deal

"No one disagrees with the ultimate objective" of the deal -- to prevent Iran from getting a nuclear weapon. Tillerson said he and Trump want to "do a full review of that agreement as well as any number of side agreements that I understand are part of that agreement."

China

"We have to step back and look at all of China's activities ... They are taking territory or declaring control of territories that are not rightfully China's ... akin to Russia's taking of Crimea. It's taking of territory that others lay claim to."

Mexico

"Mexico is a longstanding neighbor and friend of this country."

Israeli settlements

"It's going to be very difficult to create conditions at the table for parties to have any productive discussion around a settlement."

Ukraine

"I'm hopeful that ceasefires will hold, but in the absence of that then I think it is important for us to support them in the ability to defend themselves."