Jim Mattis and four other former defense secretaries called President Donald Trump’s ouster of Gen. CQ Brown and other top officers dangerous and unjustified.

Finance ministers and central bankers from the G20 top economies gather in South Africa on Wednesday and Thursday, for a meeting marred by the absence or curtailed attendance of key members and disputes over the main issues of climate, debt and inequality.

Trump announced the dismissal of Air Force Gen. Charles Q. Brown Jr. and said he would nominate Lt. Gen. Dan Caine, a retired three-star general, to succeed him as the top U.S. military officer.