With Iran’s Supreme Leader vowing revenge against the United States after the killing of General Qassim Soleimani in an overnight airstrike in Iraq, Americans committed to playing events among the European Tour’s Middle East tournament swing are paying close attention to security concerns in the region.

World No. 1 Brooks Koepka, Dustin Johnson, Phil Mickelson, Patrick Reed, Bryson DeChambeau, Patrick Cantlay and Tony Finau are among Americans scheduled to play in one or more of the region’s three events over the next month.

Koepka is scheduled to play at the Abu Dhabi HSBC Championship, Jan. 16-19, and also the Saudi International, Jan. 30-Feb. 2.

“We will monitor the new development,” Blake Smith, Koepka’s manager, told GolfChannel.com Friday. “I don’t have anything to report at this time.”

DeChambeau is scheduled to play in the Abu Dhabi Championship and again in the Omega Dubai Desert Classic the following week (Jan. 23-26).

“As of right now, Bryson is still committed, but we are monitoring the situation in the Middle East closely,” said Brett Falkoff, DeChambeau’s manager.

Count Mickelson among those whose commitment isn’t wavering with Friday’s developments. He’s scheduled to play the Saudi International.

“We intend to keep our commitment to play at this year’s event,” said Steve Loy, Mickelson’s manager.

So does Johnson, who will be the Saudi International’s defending champion.

“Please note that neither Dustin nor I will have any further comment on developments in the Middle East, although we will responsibly monitor to ensure our safety,” said David Winkle, Johnson’s manager.

The United States killed Soleimani in a drone strike near Baghdad’s Airport on Thursday. The Pentagon blamed Soleimani and his Quds Force for attacks on coalition bases in Iraq, including a Dec. 26 strike that killed an American contractor. The Defense Department also accused Soleimani of approving the attack on the U.S. embassy in Baghdad on Dec. 31.

"General Qassem Soleimani has killed or badly wounded thousands of Americans over an extended period of time, and was plotting to kill many more...but got caught!" President Donald Trump tweeted Friday. “He was directly and indirectly responsible for the death of millions of people, including the recent large number of PROTESTERS killed in Iran itself."

Iran’s Supreme Leader Ayatollah Ali Khamenei warned Friday that “harsh relation is awaiting” the United States.