WASHINGTON – The diplomatic dialogue between President Obama and Vladimir V. Putin has featured the U.S. president comparing Putin to a bored schoolboy and the Russian leader forcing an irritated Obama to wait a half-hour for a meeting.

And that was before warships from the two nations drew near in the Eastern Mediterranean amid a widening rift over Obama’s threat of a military strike against Syria after what he says is the regime’s use of chemical weapons in an area near Damascus.

With Obama in St. Petersburg today for a summit of global leaders, Putin on Wednesday denounced a potential U.S. attack on Syria as a violation of international law, while Obama told reporters the two countries’ relations have “hit a wall.”

“This is basically as bad as it gets,” said James Goldgeier, dean of the School of International Service at American University and the Russia director for the National Security Council under former President Bill Clinton. “You typically don’t have leaders who so openly criticize each other, who openly disdain each other.”

The two leaders’ public tension ends a period of improved ties between the United States and Russia after Obama came into office determined to “reset” the relationship.

Putin told the Associated Press on Wednesday that Russia “doesn’t exclude” backing a UN resolution allowing military strikes against Syria if it’s proved the regime used poison gas. Still, he targeted Obama’s request for U.S. congressional authorization to use force as a violation of international law.

“Anything outside the framework of the UN Security Council is aggression, other than self-defense,” Putin said in remarks at the Kremlin. “What Congress and the Senate are doing now is essentially legitimizing aggression. This is unacceptable.”

He also accused Secretary of State John F. Kerry of deceit in his Sept. 3 Senate testimony, with Putin arguing that al-Qaida-influenced elements are the most powerful forces in the Syrian rebellion.

“They know about it,” he said of the Obama administration. “I found it unpleasant, surprising. But he lies, and he knows he lies. It’s sad.”

Russia is temporarily bolstering its naval presence in the region to improve its surveillance capability over U.S. ships and submarines deployed in the area and to ensure security for Russian citizens residing in Syria, according to a Russian official who asked not to be named, citing policy.

Obama said at a news conference in Stockholm, where he visited on the way to the international summit after canceling a planned meeting with Putin in Moscow, that “we’ve kind of hit a wall in terms of additional progress” on critical issues.

Still, he said he hasn’t “written off” future areas where U.S. and Russian interests might intersect, and he shrugged off the deterioration in relations. The two countries should be open about their differences and not “sugarcoat them,” he said.