WASHINGTON — Sen. Marco Rubio expressed reservations about Rex Tillerson’s close relationship with Russian President Vladimir Putin shortly after Tillerson was announced as Donald Trump’s secretary of State nominee in December.

On Wednesday, the Florida Republican and one-time presidential hopeful had his chance to grill Tillerson on Capitol Hill, and he didn’t hold back.

“Is Vladimir Putin a war criminal?” Rubio asked Tillerson halfway through his first 10 minutes of questioning.

“I would not use that term,” Tillerson said.

“Mr. Tillerson, what’s happened in Aleppo is in the public domain,” Rubio said. “There is so much information out there about what’s happened in Aleppo. … It should not be hard to say that Vladimir Putin’s military has conducted war crimes in Aleppo.”

Rubio then presented evidence of dissidents, journalists and political opponents murdered under suspicious circumstances during Putin’s administration, but Tillerson said he would need to have access to classified information to determine whether the murders can be attributed to Putin.

“Do you believe that Vladimir Putin and his cronies are responsible for ordering the murder of countless dissident journalists and political opponents?” Rubio asked.

“I do not have sufficient information to make that claim,” Tillerson said. He said that it’s important “that I deal with facts” when advising President-elect Trump.

“None of this is classified, Mr. Tillerson,” Rubio replied. “These people are dead.”

“I’m not disputing these people are dead,” Tillerson said.

After Rubio’s questioning, New Jersey Democratic Sen. Bob Menendez continued to push Tillerson on calling Putin’s actions in Syria a war crime, and Tillerson countered that he needed classified information to make such a statement.

Senate Foreign Relations Committee chairman Sen. Bob Corker of Tennessee then interjected, asking Tillerson if he had classified information whether he would be willing to call Putin a war criminal.

“Yes,” Tillerson responded.

Rubio and Menendez were among the first senators to question Tillerson during hearings that began Wednesday morning and continued throughout the day, and will continue again on Thursday.

Multiple senators asked Tillerson about sanctions against Russia, something he opposed as the head of Exxon Mobil in 2014.

Tillerson clarified that he would support the current level of sanctions for now before determining whether to eliminate, reduce or add more sanctions against Russia.

A litany of foreign policy issues were addressed during the hearing, including Cuba.

Tillerson said he would advise Trump to eliminate President Barack Obama’s executive actions, but stopped short of saying Cuba belongs on the state sponsor of terrorism list.

Tillerson also said in response to questions from Sen. Tim Kaine, D-Va., that he is hopeful of a two-state solution between Israel and Palestine, although he said there are many factors outside of his control that contribute to instability in the region.

Before questioning began, Tillerson, a born and raised Texan, received introductions and praise from Texas Sens. John Cornyn and Ted Cruz, both Republicans.

“We live in a dangerous year, in a dangerous world, and Rex Tillerson is a serious man who understands the value of perseverance,” Cruz said during his testimony.

Tillerson also received an introduction from former Secretary of Defense Robert Gates, who served on the board of Boy Scouts of America with Tillerson and reportedly put Tillerson on Trump’s radar after the election as the president-elect weighed a secretary of State nominee.