White House Press Secretary Josh Earnest on Tuesday expressed his optimism that Greece and its creditors will reach a deal and market instability will be avoided.

Russian President Vladimir Putin will meet with Prime Minister Alexis Tsipras and other foreign leaders in the framework of the International Economic Forum in St. Petersburg, the president's spokesman Dmitry Peskov said on Tuesday.

"The major issue is to reach a sustainable deal. It is not a major issue for the government, it is a major issue for the country," Prime Minister Alexis Tsipras said on Tuesday in a meeting with Potami party leader Stavros Theodorakis.