( CNN ) -- The sponsor of a top golf tournament in South Korea insists it is safe to go ahead despite two American players pulling out due to security fears . U.S. Ryder Cup stars Dustin Johnson and Zach Johnson withdrew from the Ballantine 's Championship Monday , citing concerns over recent tensions between North and South Korea . `` They have reached this decision following perceived unrest on the Korean Peninsula and can no longer assure their commitment to this year 's event , '' Ballantine 's said in a statement on the website of the European Tour , which co-sanctions the tournament with the Asian Tour . Now held at the Blackstone course at Icheon , 60 kilometers south of the capital Seoul , the â‚¬2,205,000 ( $ 2.85 million ) event was the first staged in South Korea in 2008 on the island of Jeju . `` Ballantine 's and the European Tour would like to reiterate that the tournament is going ahead as planned with a full field of European , Asian and Korean PGA Tour members , '' the statement added . `` Ballantine 's has been kept fully up to date on relevant issues and the European Tour has also been liaising with key decision makers , including the Foreign Office , who have not warned of any increased risk to those traveling to or within the country . World No . 30 Zach Johnson , who won the 2007 Masters , said he did not want to take the risk following North Korea 's recent threats against its neighbor and its move to test missiles and restart its nuclear program . `` It was one of those things where the women in my life really did n't feel like it was necessary for me to go , '' the 37-year-old from Iowa told the Des Moines Register , referring to his wife , mother and young daughter . `` The posture and rhetoric that is taking place right now makes it not worth it . And it probably is just posture and rhetoric . However , I do n't want to take the chance . '' World No . 19 Dustin Johnson , who played at the Korean event in 2011 , had similar concerns . `` I feel bad for the tournament , '' said the 28-year-old , whose partner is Paulina Gretzky , the model daughter of ice hockey legend Wayne Gretzky . `` They were gracious and understanding . Hopefully it will work out in the future . '' The tournament , which starts on Thursday , will feature three former major champions in South Africa 's world No . 6 Louis Oosthuizen , South Korean veteran Y.E . Yang and Britain 's Paul Lawrie .
Dustin Johnson and Zach Johnson withdraw from golf tournament in South Korea . American golfers worried about recent tensions on the Korean Peninsula . Tournament sponsor insists that the event can safely go ahead this week . Ballantine 's Championship is co-sanctioned by European and Asian tours .