Donald Trump’s vision of a realigned U.S. foreign policy is already threatening to destabilize the current international system and force the world to reappraise America’s role in it even before Trump sets foot in the Oval Office, some top U.S. foreign policy experts are arguing.

Trump’s often disjointed and ill-informed remarks on international affairs are themselves troubling, but the deeper concern among experts is his disregard for security arrangements built on predictability and longstanding American commitments.

Phillip Lohaus, a research fellow at the American Enterprise Institute, says that in his personal experience, as he has traveled abroad over the last year, “every conversation begins and ends with Trump.”

“A lot of these people don’t understand why a candidate would seek to

change an international system that was designed by America and benefits

America,” Lohaus said. “They don’t understand why we would undermine

that when it is in our interest to keep things together.”

Whether it’s his backing away from America’s NATO commitments, his softer posture toward Russia or his more bellicose approach toward nearly everyone else, Trump is unraveling the bipartisan foreign policy consensus that has held sway for decades — and that is not going unnoticed abroad.

“He’s done serious damage to our position abroad because clearly people wonder whether he reflects an underlying sense of isolationism on the part of the United States that even if he doesn’t win the White House is far more serious than anybody thought,” said Dov Zakheim, a foreign policy adviser who has worked with Republicans on foreign policy from the Ronald Reagan administration to the Mitt Romney campaign.

Trump’s worldview– including his insistence over the weekend that Russia would not invade Ukraine (even though it already occupied Crimea) and his declarations that he would “bomb the shit” out of ISIS without much consideration for civilian casualties–has alarmed traditionally hawkish, Republican-aligned foreign policy advisers and operatives and left leaders on both sides nervous that the world is beginning to reexamine the U.S.’s position on the world stage.

Outside of the broad reshaping of America’s role, experts note that Trump is causing countries to begin discussing contingency plans just in case he’s elected.

In Japan, Lohaus said he was stunned to see a reinvigorated discussion of building up of the country’s military. Lohaus said noted serious discussions about amending the country’s Article Nine, which dictates that Japan’s only military force be for essential self defense, a post-World War II policy that has been credited with helping stabilize the region for nearly 75 years.

“They have to start thinking, ‘Maybe we need to start thinking about ourselves,'” Lohaus told TPM.

Many security experts who spoke with TPM emphasized that Trump’s words have introduced a real uncertainty among allies that the U.S. may not be as willing to help in a crisis as its past presidents have been.

“There are a number of places in the world where stability depends heavily on U.S. reliability and U.S. involvement and calling those into question can be destabilizing as other countries decide to look out for themselves,” said Philip Levy, a senior fellow on global economy at the Chicago Council On Global Affairs.

Levy pointed out that as Trump has made demonizing the Trans-Pacific Partnership a cornerstone of his campaign, U.S. allies may give more consideration to a competing alternative – the Regional Comprehensive Economic Partnership– which the U.S. is not a part of and would put China in the driver’s seat of setting Asian trade policy. While Hillary Clinton has also come out against TPP and the path to approving the deal was always narrow, Levy noted that Trump’s crusade against it in swing states like Pennsylvania and Ohio have only made “the narrow window seem even narrower.”

Trump’s lack of diplomatic decorum was noted early and often in the campaign and has sparked open letters from conservative foreign policy hawks and open rebukes from Republican congressional leaders.

“When he says the wrong things we have an obligation to speak out,” said David Kramer, a senior State Department official in the George W. Bush administration.

It began when Trump declared Mexico would be responsible for financing a Southern border wall. It devolved as he’s alienated Middle Eastern allies with suggestions that the U.S. ban Muslims from coming into the country and threatened to ditch deeply held foreign policy positions of his party. During a bizarre press conference during the Democratic convention, he went as far as to encourage Russia to intervene in the U.S. election.

Foreign policy experts say months ago they could simply tell diplomats and foreign policy advisers around the world that Trump was just a fluke, but now he is representing a major party and mainstreaming ideas that used to be on the fringe.

“It allows people in Congress to hold those views with a certain level of legitimacy that they wouldn’t have been able to have,” said Lohaus.

Sen. Ben Cardin (D-MD), the ranking member on the Senate’s Foreign Relations Committee, said as he has traveled abroad, foreign leaders tend to be “pretty diplomatic” at first when discussing Trump, but after a few drinks and in an informal setting, many of them are more candid about their concerns.

“Our allies are wondering what is going on in America,” said Sen. Ben Cardin (D-MD), told TPM in an interview. “They wonder how a person can be nominated to be president with these kinds of statements.”

When it comes to damage already done, Trump is not only forcing allies to reconsider the U.S.’s place in the world, he’s redefining his party’s positions on foreign policy.

“He’s opened up a Pandora’s box that will be very hard to close,” Zakheim said.