President Donald Trump announced on May 8, 2018 that he was pulling the United States out of the 2015 Iran nuclear deal, arguing that the international accord was not in America's "national interest." The decision threw a cloud of uncertainty over the future of the nuclear accord and raised tensions with US allies in Europe.

Britain, France and Germany lobbied the Trump administration and Congress to remain in the nuclear accord, arguing that the deal was working and a US violation without a follow up plan would be destabilizing. In European capitals, the Trump administration's withdrawal was viewed as a slap in the face of allies.

A year to the day after Trump's announcement, Iran informed the other signatories of the accord that they would no longer adhere to certain "voluntary commitments." Iranian President Hassan Rouhani said the signatory nations had 60 days to implement promises to protect Iran's oil and banking sectors or Iran would resume the enrichment of uranium.

The decision came after the United States deployed an aircraft, the USS Lincoln, along with a bomber task force to the Middle East. Washington said the deployment was intended as a "clear unmistakable message." Iran said it took action because the European Union and others "did not have the power to resist US pressure."

The Joint Comprehensive Plan of Action (JCPOA), better known as the Iran nuclear deal, was signed in 2015 by United States, China, Russia, France, Germany and Britain (P5+1) and Iran following years of negotiations. Under the international agreement, Iran agreed to dismantle its nuclear program and be subject to monitoring in exchange for the lifting of international nuclear related sanctions.

The JCPOA includes a robust monitoring, verification and inspection regime carried out by International Atomic Energy Agency (IAEA). The UN watch dog has verified Iran's compliance with the deal in 12 quarterly reports. The JCPOA allows Iran to pursue a peaceful nuclear program for commercial, medical and industrial purposes in line with international non-proliferation standards.

The Iran nuclear deal was President Barack Obama's signature foreign policy achievement. Seeking to undo nearly every Obama administration legacy, Trump came into office calling it the "worst deal ever." The Trump administration argues the nuclear deal doesn't address other unrelated issues such as Iran's ballistic missiles, regional influence, support for "terrorist" groups and human rights.

The nuclear deal and lifting of punishing nuclear related international sanctions created optimism in Iran after years of economic isolation. However, even before Trump pulled the US out of the deal, Tehran blamed the US for holding back international investment and not fulfilling its end of the bargain due to the uncertainty created by Trump's threats.

After eight years with Barack Obama, Israeli Prime Minister Benjamin Netanyahu found the US president he wanted in Donald Trump. The Israeli leader repeatedly slammed the deal despite his own military and intelligence chiefs' assessment the that JCPOA, while not perfect, was working and should be maintained. Saudi Arabia and the UAE are the other main opponents of the nuclear deal.

The EU-3 (Britain, France, Germany) have scrambled to ensure that Iran receives the economic benefits it was promised in order to avoid Tehran pulling out of the deal. As EU businesses face retaliation from the US for doing business with Iran, many are opting to avoid Iran. This would likely be a present to Chinese and Russian businesses.

The "worst deal ever": That's how Donald Trump described the 2015 landmark agreement that lifted international sanctions against Iran in exchange for the country dismantling its atomic program. In May 2018 the president followed through on a campaign promise and said he would withdraw the US from the deal, which had arisen out of painstaking multi-year negotiations.

In February 2016 then-US President Barack Obama signed the free trade agreement known as the TPP along with 11 other Pacific nations. However, it never went into effect: Shortly after taking office, Trump signed an executive order that took the US out of the deal, thus keeping it from entering into force. The scuttled TPP evolved into a new regional trade partnership — without the US.

The Paris climate accord was adopted in December 2015 after the COP 21 meeting. All 195 participating member states and the EU agreed to reduce emissions, decrease carbon output and try to rein in global warming. The US signed the accord but support was short-lived: in November 2017 Trump told the UN that the US would withdrawal from the accord at the earliest possible date, November 2019.

Trump not only has undone US participation in international climate deals but also has scrapped domestic environmental regulations. Scott Pruit, Trump's head of the Environmental Protection Agency, announced in March 2018 that Obama-era vehicle emissions standards would be rolled back. And at the very start of his term, Trump also said he would review the Clean Water Act and Clean Power Plan.

The ACA, nicknamed "Obamacare," was landmark legislation that roughly halved the number of medically uninsured Americans through program expansion and insurance mandates. Its critics, Trump among them, described it as federal government overreach that would cause skyrocketing health costs for individuals. While total repeal has failed, Republicans did do away with the mandate in 2017 tax reform.