In an extraordinary new development, top senators are saying they didn’t know President Trump had sent troops to Niger as questions swirl about the ambush that killed four US servicemen there earlier this month.

Military investigators are looking into the exact circumstances of the October 4 incident, including how Sgt. La David Johnson was separated from the 12-member team as it was ambushed by 50 ISIS fighters.

The White House said Monday it notified congressional leaders in June about 965 troops conducting counterterrorism duties in Niger and Cameroon. But senators from both parties are contradicting their assertion.

During an interview on CNN’s “New Day” Monday, Sen. Bob Casey (D-PA) was asked whether he knew there were troops in Niger. “I did not,” he responded to host Chris Cuomo.

“When you consider what happened here, the four sergeants lost their lives, I think there’s a lot of work that both parties and both branches of government need to do. Not only to stay more informed but to focus on why we’re there and what happened to get to the bottom of this.”

Several other leading senators also said they were in the dark about the operation in the western Africa nation, according to CNN.

“I didn’t know there was 1,000 troops in Niger,” Sen. Lindsey Graham, R-South Carolina, told NBC’s Chuck Todd on “Meet the Press” Sunday. “They are going to brief us next week as to why they were there and what they were doing.”

Graham also said during the interview that his longtime friend and colleague in the Senate, Arizona Republican Sen. John McCain, is frustrated, “rightly so.”

“We don’t know exactly where we’re at in the world, militarily, and what we’re doing. So John McCain is going to try to create a new system to make sure that we can answer the question (about) why we were there,” he said. “We’ll know how many soldiers are there, and if somebody gets killed there, that we won’t find out about it in the paper.”

When Senate Minority Leader Chuck Schumer was asked later on “Meet the Press” about knowing whether there were troops in Niger, he responded, “No, I did not.”

But Pennsylvania Republican, Rep. Charlie Dent, a member of the appropriations committee said he knew about the troops. “It’s not new, and lawmakers that seem to be aghast at these missions going on are simply not well-read,” he told CNN’s John Berman and Poppy Harlow. ShareTweet