Image copyright AFP Image caption Sessions was one of Trump's closest advisers during the campaign

The era of good feelings following Donald Trump's well-received speech to Congress Tuesday night lasted, oh, about 23 hours. Now Russia, and the Trump campaign's connections to it, are back in the headlines.

At this point there are a few things that are known with certainty.

Attorney General Jeff Sessions met with Russian Ambassador to the US Sergei Kislyak twice last year at a time when the then-senator was actively supporting and advising Donald Trump's presidential campaign.

After Mr Sessions was nominated to be Mr Trump's attorney general - the top US government law official - he was asked, during Senate testimony and in writing, whether he had met with anyone connected to the Russian government with regard to the 2016 elections.

"I have been called a surrogate at a time or two in that campaign, and I did not have communications with the Russians," he said during his confirmation hearings.

Now Mr Sessions has announced that he will recuse himself from all existing and future department investigations involving the Trump presidential campaign.

Behind these facts are a host of questions, and the answers are somewhat uncertain. Here are some of the most pressing.

Sergei Kislyak - why is that name familiar?

Mr Kislyak, who has served as Russia's US ambassador since 2008, made headlines earlier this year for his contacts with another prominent member of Mr Trump's inner circle, Michael Flynn. The former general, who the president named as his national security adviser, came under federal investigation for his contacts with Russian officials after the presidential campaign.

While Mr Flynn acknowledged that he spoke to Mr Kislyak in late December, he originally asserted that he did not discuss sanctions the US government had imposed on Russia in response to concerns about possible Russian meddling in the 2016 US presidential election.

Leaked reports from the intelligence community revealed that this was not the case, and the president subsequently asked for Mr Flynn's resignation.

Is it unusual for a senator to talk to an ambassador?

When asked about Mr Sessions' contacts with Mr Kislyak, a Justice Department spokesperson told the Washington Post that the senator had "more than 25 conversations" with ambassadors in his capacity as a high-ranking member of the Senate Armed Services Committee. The Post followed up by contacting the other 26 members of that committee, and the 20 who responded said they had not spoken with the Russian ambassador.

"I've been on the Armed Services Committee for 10 years," tweeted Democratic Senator Claire McCaskill. "No call or meeting with Russian ambassador. Ever. Ambassadors call members of the Foreign Relations Committee."

A closer look at Mrs McCaskill's Twitter feed revealed several instances - in 2013 and 2015 - where she wrote about meeting the Russian ambassador, however. She says those meetings were not in her capacity as a committee member and were never one-on-one.

Former Republican congressman Mike Rogers, who chaired the House Intelligence Committee, said such meetings for a senator on the committee would be "routine." Democratic Senator Joe Manchin of West Virginia expressed a similar view.

"I've met with the Russian ambassador with a group, in my capacity, with a group of other senators," he said during a television interview Thursday morning. "That's in my official capacity. That's nothing. That's my job."

If these sorts of meetings are routine, then why the evasion?

This, then, is the million-dollar question - and what Democrats in Congress and Trump opponents everywhere seem to be focusing on.

"If there was nothing wrong, why not come clean and tell the entire truth?" Senate Minority Leader Chuck Schumer asked during a press conference on Thursday morning.

Image copyright Getty Images Image caption Democrats are demanding Sessions resign

Since the Washington Post story came out, the attorney general and his representatives have offered an array of responses to this, ranging from forgetfulness to not thinking it was important/relevant.

"I never had meetings with Russian operatives or Russian intermediaries about the Trump campaign," Sessions told a news conference on Thursday afternoon.

Democrats weren't buying it.

"When Senator Sessions testified under oath that 'I did not have communications with the Russians,' his statement was demonstrably false, yet he let it stand for weeks," said Congressman Elijah Cummings of Maryland. "And he continued to let it stand even as he watched the president tell the entire nation he didn't know anything about anyone advising his campaign talking to the Russians."

During the Flynn controversy, Mr Trump defended his embattled national security adviser by saying that contacts with foreign leaders, including Russians, weren't just permissible but advisable. That defence fell apart because clear evidence came out that Mr Flynn had been evasive not only to the press and public but to the administration itself.

Mr Sessions has since said that he did indeed meet with the ambassador twice and probably should have mentioned it during his confirmation hearings, but he was responding to questions about ongoing contact with Russian operatives. Critics are saying he is parsing words. Like Flynn, the original evasion has become a bigger story than the original contacts.

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Who is currently investigating this?

There at present is an ongoing inquiry by the Federal Bureau of Investigation, along with other intelligence agencies, into possible Russian meddling with the 2016 presidential elections, including any connections to members of the Trump campaign team.

In late January FBI officials interviewed Mr Flynn, for instance, on his contacts with Mr Kislyak.

In addition, two congressional panels - the House and Senate intelligence committees - are already planning on looking into the matter, although no concrete steps have yet to be taken. They may subpoena Trump officials, including Mr Flynn, to testify on the extent of their interaction with the Russian government.

Some Democrats have called for the creation of a special "select" committee to focus solely on the investigation, rather than relying on existing committees that have other obligations. So far, these calls have not gained traction.

Others, including Mr Schumer, have demanded a special independent counsel to be named to lead the inquiry - similar to the duties performed by Kenneth Starr during the Bill Clinton administration. The danger for the White House is that these types of investigations are difficult to control and can expand greatly in scope as they progress.

The Starr investigation, for instance, started as an inquiry into an old Clinton real-estate deal and eventually ended in a recommendation that the president be impeached for lying about sexual relations with a White House intern.

Can Sessions survive?

After bipartisan calls for Mr Sessions to recuse himself from oversight, as attorney general, of the FBI's Russia investigation reached a fevered pitch, the attorney general relented. He notably said, however, that the decision was made in consultation with career Justice Department officials and was due to his involvement with the Trump campaign and not because of the recent revelations.

Media playback is unsupported on your device Media caption Jeff Sessions: The "remarks are unbelievable to me and are false"

Democrats have upped the ante, however, calling for Mr Sessions' outright resignation.

"Jeff Sessions simply does not have the confidence of the American people," tweeted Congresswoman Yvette Clarke of New York. "He should resign now."

Given the attorney general's close relationship with the president, a resignation seems unlikely. Then again, the same could be said for Mr Flynn, and he was ultimately shown the door.

What should be of particular concern to Republicans is that the Sessions revelations fit a growing pattern of obfuscation and evasion on the part of the president's inner circle when it comes to contact with the Russian government.

It's the kind of thing that will prompt more questions, more investigations and more speculation about what else is out there.