The United States’ tough stance on the North Korean regime is reportedly seeing results, as countries are shunning their ties the rogue regime, particularly since President Trump took office.

The administration has seen significant victories at the United Nations Security Council, where it secured two rounds of additional sanctions—particularly focusing on North Korean exports and the oil trade—while avoiding vetoes by China and Russia.

At the White House meanwhile, Trump has been taking a more aggressive rhetorical approach, repeatedly nicknaming Kim Jong-un as “rocket man” and strongly hinting at possible military action.

“Our country has been unsuccessfully dealing with North Korea for 25 years, giving billions of dollars & getting nothing. Policy didn’t work!” Trump tweeted on Monday:

Our country has been unsuccessfully dealing with North Korea for 25 years, giving billions of dollars & getting nothing. Policy didn't work! — Donald J. Trump (@realDonaldTrump) October 9, 2017

This came after he warned Saturday that “only one thing will work” in regards to dealing with the country:

Presidents and their administrations have been talking to North Korea for 25 years, agreements made and massive amounts of money paid…… — Donald J. Trump (@realDonaldTrump) October 7, 2017

…hasn't worked, agreements violated before the ink was dry, makings fools of U.S. negotiators. Sorry, but only one thing will work! — Donald J. Trump (@realDonaldTrump) October 7, 2017

While some media outlets and lawmakers have bristled at Trump’s words, the Wall Street Journal reported Monday that a broader U.S. strategy appears to be bringing increased pressure on the regime, with 20 nations curbing their diplomatic or business operations in the country after pressure from the State Department – pressure that began during the last days of the Obama administration and has ramped up during the Trump administration.

“U.S. officials have asked countries to shut down businesses owned by the North Korean government, remove North Korean vessels from ship registries, end flights by the country’s national air carrier and expel its ambassadors,” the outlet reported, adding that U.S. diplomats made sure that North Korea could not secure meetings at the Association of Southeast Asian Nations summit this year.

Mexico, Peru, Spain, Kuwait, and Italy have all expelled their ambassadors after U.S. highlighted North Korea’s use of embassies to ship contraband and earn currency. Other countries have agreed to reduce the presence of North Korean guest workers, the Journal reported. Guest workers were also targeted by both rounds of U.N. sanctions this year, which the U.S. says are used to earn money abroad for the regime’s weapons program.

The Journal notes that these developments suggest a more subtle behind-the-scenes campaign by diplomats parallel with U.N. sanctions and bullish talk from the White House. Some of the negotiations are small-scale, with one incident involving a North Korean hostel operating in Berlin—the German government announced in May it was closing it down after diplomats pointed it out.

Other countries who were initially skeptical—such as Saudi Arabia—reportedly fell into line this year as North Korea’s aggression heightened, particularly its test of a hydrogen bomb in August, and the U.S. puffed out its chest in response. Some countries, such as Chile and Myanmar, have still resisted the U.S. outreach, however.

Adam Shaw is a Breitbart News politics reporter based in New York. Follow Adam on Twitter: @AdamShawNY