The nuclear agreements reached at a meeting between the US and Russian leaders and their failure to iron out differences on how to tackle escalating Mideast violence and on a trade deal reflect the complexity of the bilateral relations.

Following talks in St. Petersburg, the presidents of the United States and Russia announced an agreement on cooperation in nuclear energy and another on launching a joint initiative to combat nuclear terrorism.

The Global Initiative to Combat Nuclear Terrorism calls on countries to improve accounting, control and physical protection of nuclear material and radioactive substances as well as the security of nuclear facilities, and prevent acts of nuclear terrorism.

Both sides also committed themselves to strengthening the global non-proliferation regime, and the two leaders agreed on the creation of international centers for uranium enrichment and reprocessing of spent nuclear fuel.

Russia could reap big economic gains from a potential agreement on storing spent nuclear fuel, analysts said.

US President George W. Bush, in the town for the annual Group of Eight summit that opened on Saturday, and his Russian counterpart Vladimir Putin met amid a recent flare-up in violence in the Middle East. Both leaders urged a halt to the violence.

But the two differed sharply on who was to blame for the escalation of tensions between Israel and Lebanon, with Bush blaming Hezbollah and Putin stressing that the use of force should be balanced and should stop.

Israel has stepped up air raids on Lebanese targets and blockaded Lebanese sea ports following a cross-border attack by Hezbollah guerillas during which two Israeli soldiers were kidnapped and eight killed.

Russia and the United States are members of the so-called international Quartet mediating for peace in the Middle East. The Quartet also includes the United Nations and the European Union.

The two sides also failed to cap Russia's longtime bid for membership in the World Trade Organization with a deal which was to be announced by the two leaders.

Bush said the deal is "almost reached," but more work needs to be done.

In frantic talks in Moscow and St. Petersburg, Russia agreed to allow US insurance companies access to its market.

The United States reportedly dropped a demand that foreign banks be allowed to open directly-owned branches in Russia, but wanted more Russian concessions on Boeing plane orders and access for US companies to the Shtokman oil fields.

The United States remains the last hurdle to Russia's WTO accession bid.

The Washington Post quoted Dmitri Trenin, an expert at the Carnegie Moscow Center, as saying that the failure to clinch the deal would be seen in the Kremlin as a major blow.

"They hoped, people within the government, that the US would do that and I think they feel disappointed," he said.

Russia-US relations dipped following US Vice president Dick Cheney's recent remarks that Moscow was using energy "as tools of blackmail and intimidation" of neighboring countries.

A Russian international relations expert said the recent downturn in Russia-US ties resulted not only from differences over strategic interests but also from a re-emergence of ideological differences.

But at the St. Petersburg meeting, Bush said he did not want to lecture Putin on democracy, and Putin said he would welcome discussions on democracy "in a friendly and fair way."

For all their differences, the United States and Russia share common interests in fighting terrorism and safeguarding the non-proliferation regime. And on issues like the Iranian nuclear program and the Middle East peace process, the United States is also wooing Russia for support, analysts said.

(Xinhua News Agency July 17, 2006)