Iran harshly reacted to US President Donald Trump’s decision not to certify its nuclear deal with six major powers, and Iranian President Hassan Rouhani said that Tehran might walk away if the continuing agreement does not serve the country’s national interests, Reuters reported.

Rouhani said Tehran will double its efforts to expand the country’s defense capabilities, including the country’s ballistic missile program despite the US pressure to suspend it, reported Reuters.

This comes after President Trump said in an address at the White House that he would not continue to certify the multinational agreement and warned he might ultimately terminate it.

“No president can revoke an international deal ... Iran will continue to respect it as long as it serves our interests,” Rouhani said, adding that Trump’s speech was full of “insults and fake accusations” against Iranians.

While Trump did not pull the United States out of the agreement, aimed at preventing Iran from developing a nuclear bomb, he gave the US Congress 60 days to decide whether to reimpose economic sanctions on Tehran that were lifted under the pact.

That increases tension with Iran as well as putting Washington at odds with other signatories of the accord such as Britain, France, Germany, Russia, China and the European Union, who say the US cannot unilaterally cancel the 2015 nuclear deal between Iran and world powers .

“The Iranian nation has not and will never bow to any foreign pressure... Iran’s deal cannot be renegotiated,” Rouhani said.

Reuters reported that Trump announced the major shift in US policy in a speech in which he detailed a more confrontational approach to Iran over its nuclear and ballistic missile programs and its support for extremist groups in the Middle East.