President Obama signed an executive order giving his administration powers to freeze U.S.-based financial assets and property 0f Russian officials responsible for the country's military intervention in Ukraine, the White House announced Thursday.

Meanwhile, the State Department has expanded its effort to deny visas to those responsible for or complicit in Russia's actions in the Crimea region. Those include Russian and Ukrainian officials, the State Department said.

Press secretary Jay Carney called the executive order "a flexible tool that will allow us to sanction those who are most directly involved in destabilizing Ukraine, including the military intervention in Crimea, and does not preclude further steps should the situation deteriorate."

Administration officials did not name specific individuals who will be targeted or how many would be sanctioned. They said the executive order will allow Treasury Department officials to freeze the assets of those who undermine democracy, peace and territorial integrity in Ukraine, those who misappropriate state assets and those who seize power without authorization from the interim government in Kiev.

A spokesman for House Speaker John A. Boehner's office said: "We welcome this first step, but remain committed to working with the administration to give President Obama as many tools as needed to put President Putin in check as well as prevent Russia from infringing on the sovereignty of any of its other neighbors."

The moves build on previous punitive measures from the Obama administration, including canceling planning meetings for the Group of 8 economic summit in Sochi, Russia, in June. The White House is weighing additional steps and has pressed Congress to support a $1 billion aid package for Ukraine's interim government. The House will vote on that proposal Thursday.

"We call on Russia to take the opportunity before it to resolve this crisis through direct and immediate dialogue with the Government of Ukraine, the immediate pull-back of Russia’s military forces to their bases, the restoration of Ukraine’s territorial integrity, and support for the urgent deployment of international observers and human rights monitors," Carney said.