US companies have received the final nod to go ahead with investment in Myanmar, after a period of “uncertainty”, the Wall Street Journal reports.

The move was lauded as an “important step toward openness” following a US decision to lift sanctions on the previously junta-ruled country and open up the economy for the first time in decades. Several US companies were on a race to tap the once-isolated economy but were stopped short by mixed signals from the Obama administration.

Obama has now cleared American companies to invest in Myanmar. According to the Journal, some observers worry that the US will loose it leverage and could let the country backslide into its old self. US officials said that it will continue to ban investment in military-owned sectors, expand existing sanctions, and require tighter disclosure measures.

According to AP, US companies with more than $500,000 in aggregate new investment will be required to file an annual report disclosing all their procedures on human rights, land acquisitions, environment and payments to Myanmar government entities. US companies planning to invest in state firm Myanmar Oil & Gas Enterprise have to notify the US government within 60 days.

“Easing sanctions is a strong signal of our support for reform, and will provide immediate incentives for reformers and significant benefits to the people of Burma,” President Barack Obama said in a statement.