Iranian President Hassan Rouhani (L) attends the 21st Nationwide Assembly of the Islamic Revolution Guards Corps (IRGC) Commanders in Tehran, Iran on September 15, 2015.

BAGHDAD — The top commander of U.S. forces in the Middle East says he believes the Iranians or their proxies may orchestrate an attack at any moment.

"I think the threat is imminent," Marine Gen. Frank McKenzie said in an exclusive broadcast interview with NBC News in the Iraqi capital. "We continually evaluate our force posture in the region."

The U.S. has beefed up its military presence in the region in an effort to deter Iran and protect American forces and allies.

Over the last month, the Trump administration announced that it was sending an aircraft carrier strike group and Air Force bombers to the Middle East, as well as Patriot missiles and additional troops, amid heightened concerns of an Iranian attack.

McKenzie stressed that tensions remain high.

"I don't actually believe the threat has diminished," McKenzie said after holding a series of meetings with the Iraqi prime minister and defense chief. "...I believe the threat is still very real."

McKenzie said he was "heartened" by the efforts of the Iraqi government to protect American forces and its allies in the region. Roadside bombs have posed the major danger to American forces in Iraq, McKenzie added, but he said the threat from the Iranians is evolving.

"They probe for weakness all the times," McKenzie said. "I would say the threat has probably evolved in certain ways even as our defensive posture has changed and become more aggressive, and we certainly thank our Iraqi partners for many of the things they've done."

"I think we're still in the period of what I would call tactical warning," he said. "The threat is very real. "

McKenzie declined to go into specifics on the nature of the threats.