BAGHDAD — On the eve of international talks over Iran’s disputed nuclear program, the leader of the U.N. nuclear monitoring arm announced what appeared to be a significant concession from Tehran.

Yukiya Amano, the director general of the International Atomic Energy Agency, said Tuesday that, despite unspecified differences, he expected a deal “quite soon” on arrangements for an investigation into potential military applications of the program.

The tentative accord — announced as envoys headed to the Iraqi capital to resume negotiations today — is likely to be used by Iran as added leverage to seek concessions from the West on sanctions.

But U.S. officials have shown no willingness to shift into bargaining mode so quickly.

The flurry of diplomacy reinforced the shift of focus to talks from the possibility of military action by Israel, but mixed messages from Iran — including sharp statements from political figures and today’s planned satellite launch using a large missile — kept uncertainty high.

The IAEA and world powers are involved in separate talks with Iran: The nuclear agency is seeking access to Iran’s Parchin military site, which the nuclear agency suspects has been used for secret tests for potential triggering mechanisms for nuclear weapons, while the Baghdad talks are to focus on limiting Iran’s enrichment of uranium.

A major breakthrough in the impasse was not expected, with officials and experts saying both sides will seek to demonstrate enough progress to keep the process moving forward. That could cool down worries in international markets over possible military action, but reinforce the suspicions of Israeli leaders who claim Iran seeks only to buy time to keep up its production of nuclear fuel.

Iran’s envoys, meanwhile, promoted the Baghdad round as an opportunity to set aside past obstacles. For its part, Tehran is seeking reciprocal concessions like an easing of broad economic sanctions — including an embargo on oil deals starting July 1 and broad banking restrictions — at the Baghdad talks.

Amano’s report of progress, however, elicited a skeptical response from Israel and the United States. Israel considers Iran a threat to its existence and has threatened to bomb Iran’s nuclear installations.

Ehud Barak, Israel’s defense minister and a key architect of its hard-line policy on the Iranian nuclear program, said that Iran seemed to be trying to “create the impression of progress” to “remove some of the pressure” before the Baghdad talks and to “put off the intensification of sanctions.”

He reiterated Israel’s position that Iran should not be allowed to enrich uranium at all and that all enriched uranium should be removed from the country, though he appeared to recognize the talks would not hold such a firm line.

White House press secretary Jay Carney called the announcement a “step forward” and “a step in the right direction.” But he stressed that the administration will “make judgments about Iran’s behavior based on actions, not just promises or agreements.”

“We judge and will judge Iran by its actions,” Carney said, adding that “we’re not at the stage of negotiating what Iran would get in return for fulfillment of its obligations.”

The Baghdad talks, involving the five permanent U.N. Security Council members — Britain, China, France, Russia and the United States — plus Germany, could offer a test of how much the U.S. and allies are willing to bend from demands for Iran to halt to all enrichment and instead concentrate on just stopping the highest-grade production.

The West and others fear the 20 percent-level enrichment can be turned quickly into weapons-grade of over 90 percent.

Iran has repeatedly denied it seeks nuclear arms and says its reactors are only for power and medical research.

On Tuesday, the official Islamic Republic News Agency reported that Iranian scientists had inserted a domestically made fuel rod, which contains pellets of 20 percent enriched uranium, into the core of a research nuclear reactor in Tehran.

The advance would be another step in achieving proficiency in the nuclear fuel cycle. Iran said in January that it had produced the first nuclear fuel rod, and that it had to find a way to make them because Western sanctions prohibit their purchase from foreign markets.

Western claims about a clandestine atomic weapons program have often cited Iran’s Parchin military facility, where the U.N.’s International Atomic Energy Agency believes Iran in 2003 ran explosive tests needed to set off a nuclear charge. Iran describes Parchin as a conventional military site.

This report contains information from the New York Times and The Associated Press.