Ambassadors are crucial for diplomacy, especially in the midst of a rapidly changing world, but Donald Trump has surprisingly few of them in place in key nations.

Since taking over the White House back in January, only three of Trump's ambassadorial nominees have been confirmed.

Trump attacked Democrats for obstructing his nominees as they face hearings and votes, he said: "Dems are taking forever to approve my people, including Ambassadors. They are nothing but OBSTRUCTIONISTS! Want approvals."

However, there has been a lack of nominations coming from the Oval Office for the senate to look into.

According to the American Foreign Service Association (AFSA), only 11 positions have been filled or nominated for.

Once a nomination is made, official paperwork must be sent to the Senate Foreign Relations Committee. They then process the documents, hold a hearing with the nominee and vote on whether to send the prospective ambassador to the senate for a full vote.

As it stands, three of Trump's picks have passed the full nomination process. Former South Carolina governor Nikki Haley has been posted to the UN. Trump's former bankruptcy lawyer David Friedman is representing Israel. Former Iowa governor Terry Branstad is set to begin his role as the Chinese ambassador in the coming weeks.

It comes after the acting Chinese ambassador, David Rank, resigned after Trump's decision to withdraw from the Paris Climate Accord.

There have also been growing tensions in the wake of the London terror attacks, as the acting US ambassador in London, Lewis Lukens put out a series of tweets commending mayor Sadiq Khan.

"I commend the strong leadership of the mayor of London as he leads the city forward after this heinous attack," the acting ambassador said.

This came as Donald Trump criticised the mayor in two separate tweets which lead Sadiq Khan to call for the president's October state visit to be cancelled. The White House denied that it was looking for a fight between the two.

Donald Trump
Dozens of key posts remain empty in Trump's administration Nicholas Kamm/AFP/Getty Images

Five Trump picks are currently making their way through the confirmation procedure, but paperwork issues from the president's end have caused delays.

Senator Ben Cardin (D-MD) is the ranking Democrat on the Senate Foreign Relations Committee who oversees the votes and hearings. His spokesman said: "The President should get off Twitter and lead his team in sending more ambassadors and other crucial nominees to the Senate. We're ready to do our job, but he needs to do his first."

Currently, there are 67 'vacant' posts. When there is no ambassador, a chargé d'affaires fills the role while ambassadors from the previous administration often continue in their posts.

But amid a rise in global tensions between the US and North Korea as well as the EU/Germany and the US, there remains no ambassador to posts for South Korea, Germany and key nations in the Middle East.

Several names have been floated, but none have been officially nominated, including the proposed UK ambassador Woody Johnson.

According to AFSA, the Obama administration had 16 nominations by the turn of his first 100 days in 2009.