Donald Trump pledged Monday that he would keep open the option of using enhanced interrogation techniques in order to collect intelligence critical to protecting the United States.

"I have made it clear in my campaign that I would support and endorse the use of enhanced interrogation techniques if the use of these methods would enhance the protection and safety of the nation," he wrote in an op-ed for USA Today. "Though the effectiveness of many of these methods may be in dispute, nothing should be taken off the table when American lives are at stake."

"The enemy is cutting off the heads of Christians and drowning them in cages, and yet we are too politically correct to respond in kind," he said.

Trump admitted that the use of techniques such as waterboarding have been controversial, and said the decision would weigh heavily on any president. But he said he'd use those techniques nonetheless.

"The people of the United States expect their president to make such decisions, and I will not disappoint them," he wrote. "I will do whatever it takes to protect and defend this nation and its people."

"I cannot imagine knowing that something could have been done to save American lives and then not taking those actions," he wrote. "Ultimately, the president must live with those decisions, and I know that the American people would expect me to act with intention, will and courage on their behalf."