(CNSNews.com) – Russian President Vladimir Putin said last week he is ready to meet with President Trump “as soon as the U.S. side is ready,” and now the administration has confirmed that National Security Advisor John Bolton will visit Moscow in the coming days “to discuss a potential meeting” between the two.

National Security Council spokesman Garrett Marquis said on Twitter Bolton will travel to Moscow, as well as to London and Paris, from June 25-27.

Asked at the White House whether he was planning to meet with Putin next month – when he is scheduled to travel to Europe – Trump told reporters, “we’re looking at the possibility.”

Trump is due to attend a NATO summit in Brussels on July 11-12, followed by a long-planned visit to Britain on July 13.

Russia is likely to feature in both itineraries, given the poor state of NATO-Russia relations over Ukraine, missile defense and other issues, and tensions between Britain and Russia over a nerve agent attack on a former Russian spy in Salisbury, England last March.

Trump’s critics at home and abroad accuse him of being soft on Putin, pointing to comments such as his recent suggestion that Russia be re-admitted to the group of leading industrial nations – four years after it was suspended from what was then the G8 in response to its annexation of Crimea.

The comment contributed to tensions between Trump and G7 partners at the group’s summit in Quebec earlier this month.

During his campaign for the White House in 2016, Trump’s approach to Putin brought sharp criticism, both from his Republican primary challengers and from Democratic candidate Hillary Clinton.

After his election, the then-president elect told Putin in a phone call he was “very much looking forward to having a strong and enduring relationship with Russia,” while the Kremlin said the two “not only agreed on the absolutely unsatisfactory state of bilateral relations but also expressed support for active joint efforts to normalize relations.”

Yet the U.S.-Russia relationship has been a difficult one since Trump took office.

Less than three months later, Trump ordered a cruise missile strike on a Syrian airbase which U.S. intelligence linked to a chemical weapons attack.

In taking direct military action against Putin’s close ally in Damascus, Trump did what President Obama had not done in response to earlier chemical weapons use by the Assad regime. (Obama instead assented to a Russian-brokered deal to remove the regime’s declared chemical weapons stocks.)

Putin accused the U.S. of either being taken in by, or being part of, a conspiracy by anti-Assad rebels. He called for an investigation into the possibility that the toxic gas attack was “a staged provocation, a deliberate incident designed to create a pretext for increasing pressure on the legitimate Syrian authorities.”

Trump and Putin met last summer on the fringes of a G20 summit in Germany, where some progress was made on de-escalation and deconfliction efforts in Syria. Last November they met again, on the sidelines of an APEC leaders’ meeting in Vietnam.

But in March this year – just days after a phone conversation following Putin’s re-election – Trump expelled dozens of Russian diplomats in solidarity with Britain after the nerve agent attack in Salisbury.

The following month, the administration imposed sanctions against 17 senior Russian government officials and a handful of oligarchs close to Putin, along with their companies.

Days later, after another chemical weapons attack in Syria, Trump ordered a second and larger military response. Together with Britain and France, the U.S. launched missiles from warships and aircraft to target three regime chemical weapons-linked installations.

Even as Trump has continued to talk and tweet about the importance of cooperation with Russia to deal with major issues around the globe, administration officials have delivered some of the sharpest criticism of Russian policies in years, especially at the State Department and at the United Nations in New York.

Last week, Putin said he was ready for a face-to-face meeting with Trump “as soon as the U.S. side is ready.”

“The president of the United States has repeatedly said that he considers this meeting expedient, and I agree that this is indeed the case,” he told Russian reporters in China, adding that the two shared concerns about a renewed arms race.

Putin said the Russian foreign ministry and State Department should work together, but that “personal meetings are certainly necessary as well.”

“As soon as the American side is ready, this meeting will be held immediately, depending on my work schedule.”