President Trump has ordered his administration to draw up formal demands for Germany, Japan and all other countries hosting American troops to pay the full price of US soldiers deployed on their soil, along with a 50% premium for the privilege of hosting them, reports Bloomberg, citing a dozen administration officials and people briefed on the matter.

President Donald Trump speaks to troops at Ramstein Air Base, Germany, Thursday, Dec. 27, 2018. (Photo by Brian Ferguson via Stars and Stripes)

In some cases, nations hosting American forces could be asked to pay five to six times as much as they do now under the “Cost Plus 50” formula. -Bloomberg

Trump has long-complained that countries hosting US troops aren't paying enough, to the point where he nearly derailed recent talks with South Korea over how much they're paying for the 28,000 US troops on their soil - overruling his negotiators and telling National Security Advisor John Bolton "We want cost plus 50."

The president’s team sees the move as one way to prod NATO partners into accelerating increases in defense spending -- an issue Trump has hammered allies about since taking office. While Trump claims his pressure has led to billions of dollars more in allied defense spending, he’s chafed at what he sees as the slow pace of increases. -Bloomberg

"Wealthy, wealthy countries that we’re protecting are all under notice," said Trump during a January 17 speech at the Pentagon. "We cannot be the fools for others."

Jens Stoltenberg, NATO Secretary General, just stated that because of me NATO has been able to raise far more money than ever before from its members after many years of decline. It’s called burden sharing. Also, more united. Dems & Fake News like to portray the opposite! — Donald J. Trump (@realDonaldTrump) January 27, 2019

Bloomberg's sources caution that the idea is "one of many under consideration," in order to try and convince US allies to pay more, and the plan may be toned down. That said, "it has sent shock waves through the departments of Defense and State, where officials fear it will be an especially large affront to stalwart US allies in Asia and Europe."

Other current and former administration officials "describe it as far more advanced than is publicly known," reports Bloomberg. In addition to seeking more money from allies hosting US troops, the Trump administration wants to use the new policy as means of leverage over countries to do what the US demands overseas.

As evidence, they say officials at the Pentagon have been asked to calculate two formulas: One would determine how much money countries such as Germany ought to be asked to pay. The second would determine the discount those countries would get if their policies align closely with the U.S. -Bloomberg

The warning to South Korea was a deliberate move, says Victor Cha, a senior adviser at the Center for Strategic and International Studies in Washington. By demanding "Cost Plus 50" from Seoul, Trump is signaling a paradigm shift.

"We have a more integrated military with South Korea than with any other ally," said Cha. "To send this message to a front-line Cold War ally is trying to say very clearly that they want a paradigm shift with the way they do host-nation support."

Others think that the "Cost Plus 50" plan will spark debates within allied governments over whether they even want US troops on their soil. Both Germany and Japan, two of the three defeated WWII Axis powers, have long-resisted the presence of American troops on their soil. Other countries such as Poland, on the other hand, welcome US troops.

Germany currently pays around 28% of the costs of US forces on German soil - or around $1 billion per year. Under the "Cost Plus 50" plan, their payment would skyrocket - along with payments from Japan and South Korea.

"You start tipping over rocks and see what crawls out and you’ve got to be ready for it," said American Enterprise Institute defense policy expert MacKenzie Eaglen. "You’re going to see domestic political debates wrapped around these military bases once you reopen the discussion."

Trump has been musing about the idea that countries should pay the full cost, plus a premium, since taking office. His ambassador to the European Union, Gordon Sondland, said it’s all about making sure other countries have “skin in the game.” “If you have countries which clearly can afford to do it and are not doing it because they think we’ll just step in and do it for them, the president has a problem with that,” he said in an interview. Sondland declined to say which countries would be targeted and wouldn’t elaborate when asked specifically about the “Cost Plus 50” approach. -Bloomberg

The "Cost Plus 50" plan reportedly originated at the National Security Council - however officials have declined to confirm or deny the proposal.

"Getting allies to increase their investment in our collective defense and ensure fairer burden-sharing has been a long-standing U.S. goal," said NSC spokesman Garrett Marquis. "Getting allies to increase their investment in our collective defense and ensure fairer burden-sharing has been a long-standing U.S. goal."

Critics of the plan say it ignores the benefits the US enjoys from having US troops stationed abroad.

"Getting allies to increase their investment in our collective defense and ensure fairer burden-sharing has been a long-standing U.S. goal," said former US Ambassador to NATO, Douglas Lute. "The truth is they’re there and we maintain them because they’re in our interest."

In Germany, for instance, the U.S. relies on several crucial installations: the Landstuhl Regional Medical Center and the Ramstein Air Base. Landstuhl is a world-class medical facility that has provided emergency care to U.S. soldiers wounded in Iraq and other trouble spots. Germany is also home to the headquarters of the U.S. Africa Command. Estimating how much Germany ought to pay for those bases, which serve so many other interests, would be complicated. -Bloomberg

"There are a lot of countries that would say you’ve got it absolutely wrong -- you think we’re going to pay for this?" said former deputy assistant secretary of defense, Jim Townsend, who added: "I hope cooler heads prevail."