Washington - US president-elect Donald Trump on Wednesday accused Barack Obama of making "inflammatory" statements and complicating the impending transfer of power - the latest salvo in an escalating war of words with the current commander-in-chief.
The unorthodox personal and public criticism of a sitting president comes less than a month before the 70-year-old Trump - who defeated Obama's preferred successor Hillary Clinton in November's presidential election - takes office.
"Doing my best to disregard the many inflammatory President O statements and roadblocks," Trump wrote on Twitter.
Doing my best to disregard the many inflammatory President O statements and roadblocks.Thought it was going to be a smooth transition - NOT!— Donald J. Trump (@realDonaldTrump) December 28, 2016
The social media jab is the latest from the 70-year-old real estate mogul aimed at Obama, in what has become a most unconventional transition between the outgoing Democrat and the incoming Republican leader.
Obama said in an interview released earlier this week that he could have been re-elected for a third term if he had been eligible and that the nation still largely embraces his political vision.
"I am confident in this vision because I'm confident that if I had run again and articulated it, I think I could've mobilised a majority of the American people to rally behind it," Obama told the interviewer, his former senior adviser David Axelrod.
It was not immediately clear what exactly Trump was referring to in the first tweet, but minutes later, he took Obama to task over his policy on Israel.
We cannot continue to let Israel be treated with such total disdain and disrespect. They used to have a great friend in the U.S., but.......— Donald J. Trump (@realDonaldTrump) December 28, 2016
"Not anymore. The beginning of the end was the horrible Iran deal, and now this (UN)! Stay strong Israel, January 20th is fast approaching!"
Last week, the UN Security Council passed a resolution demanding a halt to Israeli settlement building in Palestinian territory.
The United States declined to use its veto, instead abstaining and thus enabling the adoption of the first UN resolution since 1979 to condemn Israel over settlement policy.
Trump, who takes office on January 20, had publicly called for the United States to veto the resolution and has repeatedly criticised Obama's approach.