ST. PETERSBURG, Russia (AP) — Russian President Vladimir Putin on Friday bemoaned troubled relations with the United States, saying Russia wants to improve them but is effectively held hostage by the disputes surrounding President Donald Trump.

Putin's comments in a meeting with top editors of international news agencies underlined how Russia's once-high hopes for improved relations under Trump have eroded. Although the Trump administration has imposed sanctions on Russia and expelled scores of its diplomats, Russian politicians generally portray Trump as blocked by domestic opposition from fulfilling his campaign promises of improving relations with Moscow.

Earlier in the day, speaking at an annual economic forum, Putin sharply criticized Trump's decision to pull out of the Iranian nuclear deal, saying it could trigger dangerous instability.

The Russian leader said the U.S. withdrawal from the 2015 agreement came even as the international nuclear watchdog confirmed that Tehran was fulfilling its obligations. "What should it be punished for, then?" Putin asked.

Trump's administration has demanded that Iran stop the enrichment of uranium and end its involvement in Syria, Yemen, Lebanon and Afghanistan in order to negotiate a new deal.

"If international agreements are revised every four years it would offer zero horizon for planning," Putin said. "It will create the atmosphere of nervousness and lack of trust."

In the meeting with editors, Putin declined to assess relations between Trump and North Korea's Kim Jong Un, but said the United States should not try to take a hard line with the country.

"In order to talk about a full denuclearization of North Korea, I believe we should give North Korea a guarantee of their sovereignty and inviolability," the Russian president said. "I am deeply convinced that if you don't impose anything, if you don't behave aggressively and if you don't corner North Korea, the result that we need will be achieved faster than many would think, and at less cost."

Putin also expressed frustration at having little contact with Trump and faulted the investigation into whether there was collusion between Trump's campaign and Russia and whether Russia tried to interfere with the 2016 U.S. election.

"We are hostages to this internal strife in the United States," Putin said. "I hope that it will end some day and the objective need for the development of Russian-American relationships will prevail."

At the economic forum, Putin also engaged in a tongue-in-cheek exchange with French President Emmanuel Macron, saying with a smile that Russia could help protect Europe if its rift with the U.S. widens over Iran.

"Don't you worry, we will help ensure your security," Putin said. Macron responded on a serious note that France and its allies could stand for themselves.

In his speech at the forum and during talks with Putin on Thursday, Macron called for closer ties between France and Russia despite their differences.

Japanese Prime Minister Shinzo Abe also spoke at the forum and called for closer cooperation with Russia.

The presence of Macron and Abe and their statements in favor of cooperation were important for Putin, indicating that the U.S.-led efforts to isolate Russia face increasing obstacles.

The U.S. and its allies have hit Russia with several waves of sanctions that badly hurt its economy.

Putin sharply criticized the sanctions, saying they signal "not just erosion but the dismantling of a system of multilateral cooperation that took decades to build."

Putin told the editors that he would observe constitutional term limits that would prevent him from running for a new term in 2024. However, some observers have suggested he might seek to have the constitution changed.

On tensions with Britain over allegations that Russia was behind the March poisoning of a Russian former spy in Britain, Putin said there should "either be a joint, full-value, objective investigation or simply stop talking about this subject because it doesn't lead to anything except worsening relations."

Russia has repeatedly demanded that Britain let it take part in investigating the case.

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Associated Press writers Vladimir Isachenkov and Jim Heintz in Moscow contributed.

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