WASHINGTON (AP) — President Donald Trump's national security adviser warned U.S. adversaries on Wednesday that the U.S. is prepared to respond offensively to cyberattacks on the United States.

John Bolton said that even before the administration released its cyber strategy last year, Trump had issued a classified executive order effectively reversing the Obama administration's approach to offensive cyber operations. He said Trump has reduced red tape and procedural restrictions to make it less cumbersome for the U.S. to take offensive action in response to cyberattacks.

"I think that's critical, because I think that if our adversaries can take steps against us in cyberspace and feel no consequences, feel no pain, bear no costs, they have no incentive to stop attacking us in cyberspace," Bolton said at an event in Washington hosted by the Alexander Hamilton Society.

"The objective is not to have unrestricted cyber warfare, the object is to create structures of deterrence by making our adversaries understand that when they engage in offensive cyberactivities themselves, they will bear a disproportionate cost — so they think about it a lot harder before they launch a cyber operation to begin with."

At the event, Bolton answered questions on a wide-ranging number of issues.

On Iran, Bolton said that while Tehran has been able to mitigate the impact of earlier sanctions, it is feeling heavy consequences from the sanctions the U.S. has re-imposed since May when Trump withdrew from the 2015 nuclear deal Iran signed with the U.S. and other world powers.

Blaming the United States, President Hassan Rouhani warned Iranians on Wednesday they could face more economic difficulties in the months ahead.

On Monday, the U.S. is re-imposing more sanctions on Iran's oil, gas and banking industries. The U.S. also is imposing penalties for countries and companies in Europe, Asia and elsewhere that do not halt Iranian oil imports.

Bolton said the U.S. knows that some countries can't quickly stop buying oil from Iran altogether, indicating that the U.S. will be willing to give them more time.

"We don't want to harm friends and allies either," Bolton said. But he added: "The president has said unmistakably that our goal is maximum pressure and that it would drive Iranian oil exports to zero."

Bolton also said the Trump administration expects the Saudi government to fully investigate the death of Saudi critic and Washington Post columnist Jamal Khashoggi, who was killed Oct. 2 at the Saudi Consulate in Istanbul.

He did not disclose details of any actions the U.S. might take in response to the killing, which has strained relations with Saudi Arabia, a close ally of the United States.

"We expect there to be accountability for what happened, which was criminal without any question, and they have promised to do that," Bolton said. "They have promised to do that. They have gone a long way already and we'll see what the next steps are."