Viewers spot moment Hillary Clinton laughs after Donald Trump makes promise during inauguration speech

Hillary Clinton made sure to steal a glimpse of Donald Trump's spotlight today at this official inauguration ceremony.

After being sworn in as 47th president of the United States, the Republican candidate delivered a lengthy speech - one aspect of which left his former Democratic opposition in stitches.

But by the sounds of things, only a handful of viewers noticed...

Trump made his inaugural speech today (CHIP SOMODEVILLA/POOL/AFP via Getty Images)

Following his vows, Trump, 78, addressed the nation, promising to bring back the 'Golden Era' of America, as both a 'peacemaker' and a 'unifier'.

One section of the father-of-five's speech was designated for discussing foreign policy, including borders and immigration.

Earlier today, Trump vowed to sign a controversial executive order which would declare a 'national emergency' at the US-Mexican border, claiming in his speech that illegal entry to America would 'immediately be halted'.

Much to the heartache of millions of viewers, he added that 'criminal aliens' would be returned' where they came from.

Elsewhere, Trump suggested renaming the Gulf of Mexico to the 'Gulf of America' - something he'd previously suggested at a press conference at Mar-a-Lago, Florida, where he called it a 'beautiful name'.

"And it’s appropriate," he added at the time.

The same remark was made during his inauguration speech - much to the amusement of his former opposer, Hillary Clinton.

"A short time from now, we will be changing the name of the Gulf of Mexico to the Gulf of America," Trump vowed. "And we will be restoring the name of a great president, William McKinley, to Mount McKinley, where it should be and where it belongs."

As we say, the plan was a source of comedy for former presidential candidate Clinton, who went head-to-head with Trump back in 2016.

The 77-year-old could be seen giggling - her shoulders bobbing - following the controversial comment, seemingly mocking Trump for views.

Taking to social media, other eagle-eyed viewers revealed that they'd noticed the same thing.

"Bloody brilliant!" one said of Clinton's reaction.

"I know Kamala was trying to maintain that serious face," another joked.

Hillary could be seen smirking (Ricky Carioti/The Washington Post via Getty Images)

A third went on to tease: "Let her have her little moment."

"I’d have laughed if I’d been there and not just at that , there was much to laugh at and much that needed fact checking. But a lot that is very dangerous," another wrote of Trump's speech.

"I loved watching her and Bill throughout this speech. And she didn’t hold back," added a fifth.

The Clintons were also joined by former president Barack Obama at the festivities, as well as George W. Bush and his wife Laura.