The United States tightened sanctions Thursday on Myanmar's military rulers, and President George W. Bush urged countries like China and India to do more to help end a violent crackdown on anti-government demonstrators.As the U.S. Treasury Department froze any U.S. assets of 14 top military junta members, the White House urged the regime to let Myanmar-bound U.N. envoy Ibrahim Gambari meet with protest leaders and detained democracy leader Aung San Suu Kyi.In a previously unannounced meeting, Bush told Chinese Foreign Minister Yang Jiechi he hoped Beijing would “use its influence in the region to help bring a peaceful transition to democracy in Burma,” national security spokesman Gordon Johndroe said. The United States calls Myanmar by its previous name, Burma.Bush also thanked Yang, who was at the White House for talks with U.S. national security advisor Stephen Hadley, for China's help in facilitating Gambari's visit to Myanmar, Johndroe told reporters.Earlier, Bush urged “all nations that have influence” with Myanmar to back global efforts to end the crackdown, which killed nine people, including a Japanese photographer, in its second day. U.S. officials did not deny that Bush's message was largely aimed at China and India, Myanmar's powerful neighbors.“I call on all nations that have influence with the regime to join us in supporting the aspirations of the Burmese people and to tell the Burmese junta to cease using force on its own people, who are peacefully expressing their desire for change,” Bush said in a statement released by the White House.“The world is watching the people of Burma take to the streets to demand their freedom, and the American people stand in solidarity with these brave individuals,” Bush wrote. “I urge the Burmese soldiers and police not to use force on their fellow citizens. I call on those who embrace the values of human rights and freedom to support the legitimate demands of the Burmese people.”White House spokeswoman Dana Perino urged Myanmar's leaders to give Gambari “full access to all relevant parties while he is in Burma, beginning tomorrow. This includes those jailed by the junta, religious leaders, and Aung San Suu Kyi.