U.S. President Donald Trump must clarify the reasons behind his perceived “bromance” with Russia President Vladimir Putin in order to effectively repair relations between Washington and Moscow, former U.S. Defense Secretary William Cohen told CNBC on Monday.

“There is a cloud hanging over the Trump administration saying what is the nature and the basis of this bromance (with President Putin)?” Cohen asked when speaking at the China Development Forum in Beijing.

Tensions between Russia and the U.S. have been strained since Russia annexed Crimea in 2014, with Washington imposing sanctions on Moscow.

However, despite hopes from both administrations that relationships could be improved as a result of Trump’s election victory, many observers feel the ties have regressed to levels of hostility not seen since the Cold War era.

Cohen argued the healing process between the two countries could only begin once Trump adopted a transparent approach when it comes to his financial affairs.

“The president should be asked three questions, number one, what do you own? Number two, what do you owe? And three, to whom you owe it? And if you resolve those issues then you remove the cloud (as) we all want a better relationship with Russia,” Cohen said.