The United States announced Thursday that top officials will fan out starting next week to China, the United Arab Emirates, and other key countries in support of tighter sanctions against Iran.
"China is of concern to us in this regard," Robert Einhorn, the US State Department's special adviser for nonproliferation and arms control, told the House Oversight and Government Reform Committee.
Einhorn said he and Deputy Assistant Secretary of the Treasury for Terrorist Financing and Financial Crimes Daniel Glaser would visit China at the "end of August" as part of a push to "raise this at the highest levels."
"We need for them to enforce the Security Council resolutions conscientiously and we also need for them not to 'backfill' when responsible countries have distanced themselves from Iran," he said.
Glaser and Einhorn were first bound for Japan and South Korea next week as part of a push by Washington to get its partners in Asia, the Middle East and South America to tighten the vise on Iran over its suspect nuclear program.
A top US Treasury official in charge of sanctions, Stuart Levey, will head to the United Arab Emirates, Lebanon, and Bahrain next month, while another will travel to Brazil and Ecuador, according to the department.
A top international affairs and trade official at the US Government Accountability Office, the US Congress's investigative arm, said China was "aggressive" in investing in Iran's energy sector despite the sanctions.
The official, Joseph Christoff, told the same hearing that the United States had to "turn our attention" to China because international and unilateral sanctions were "not changing their behavior."
"The Chinese will argue that they have important security needs" related to getting energy for their booming economy, said Einhorn. "In our view they are overachieving in terms of their energy security needs."
"We think they have to rebalance their priorities," said Einhorn, who underlined that China "is going to be the focus of very high-level attention over the next weeks and months" on the issue of Iran.
Christoff also called for "a concerted focus on the United Arab Emirates," which has historically close ties to Iran and "is now the number one exporter of goods and services" to the Islamic Republic.
The lawmakers were weighing the effectiveness of recent legislation aimed at sharply tightening the economic grip on Iran over what the West charges is a covert nuclear weapons program and Tehran insists is a civilian power effort.
Republican Representative Dan Burton said he was "not optimistic it is going to work" because of the president's power to waive key sanctions in the name of national security.
"This may be one of the last chances we have," said Burton, who drew parallels to Adolf Hitler's rise in 1930s Germany and warned Iranian President Mahmoud Ahmadinejad "can be equated with, possibly, Hitler."
Democratic Representative Dennis Kucinich heaped scorn on US officials whose warnings about military action against Iran suggest they think "we can afford still another war" with US troops still in Iraq and Afghanistan.
"What we ought to be looking for is a more effective means to engage Iran," he said. "It's pretty clear that sanctions have been proved to be a failed policy."
The United States has hailed a new round of UN sanctions against Iran, as well as fresh sanctions adopted by the US Congress, and punitive steps taken by the European Union, Australia, and Canada.
The moves aim to get Iran to freeze its uranium enrichment program and revive moribund talks between Iran and six world powers -- Britain, China, France, Germany, Russia and the US.
Einhorn said US Secretary of State Hillary Clinton could soon announce steps against an handful of companies that fell afoul of US laws that prohibit doing business in Iran, notably its energy sector.
"I would say that she, before very long, will have to make determinations under the law as to the sanctionability of this relatively small number of cases, fewer than 10," he said.
Clinton slams 'disrespectful' Koran-burning plans