Shortly after the Cowboys' heartbreaking loss to the Packers on Sunday, team owner Jerry Jones revealed that he won't tolerate players who refuse to stand for the national anthem. Jones told reporters that any player who disrespects the national anthem will not be allowed to play for the Dallas Cowboys.

"If there is anything disrespecting the flag, then we will not play," he said, according to Brandon George of the Dallas Morning News. "Period. We're going to respect the flag and I'm going to create the perception of it."

Jones added that he believes standing for the anthem is a rule.

"We cannot in anyway give the implication that we tolerate disrespecting the flag," Jones said, according to George. "We know that there is a serious debate in this country about those issues, but there is no question in my mind, that the [NFL] and the Dallas Cowboys are going to stand up for the flag.

"But let me be real, real clear: The thing that the National Football League needs to do and the Dallas Cowboys are going to do is stand for the flag. We're going to do that. It's the rules that are on the book in my opinion."

It's unclear how Jones feels about those who raise their fists during the anthem.

Jones also cited his phone conversation with Donald Trump, who told Jones about a supposed NFL policy that requires players to stand for the national anthem.

So, is there a policy that requires players to stand for the anthem? According to Sports Illustrated, the NFL's game operations manual says the following about the national anthem:

The National Anthem must be played prior to every NFL game, and all players must be on the sideline for the National Anthem. During the National Anthem, players on the field and bench area should stand at attention, face the flag, hold helmets in their left hand, and refrain from talking. The home team should ensure that the American flag is in good condition. It should be pointed out to players and coaches that we continue to be judged by the public in this area of respect for the flag and our country. Failure to be on the field by the start of the National Anthem may result in discipline, such as fines, suspensions, and/or the forfeiture of draft choice(s) for violations of the above, including first offenses.

So, according to that paragraph, players "must" be on the sidelines during the national anthem and "should" stand for it. However, at the end of that paragraph, you'll see that it uses the word "may" -- not "will" -- when addressing the topic of fining or suspending players who aren't on the field. Also of note: The topic of fines and suspensions is only addressed in the context of failing to be on the field by the start of the anthem. The topic is not addressed in the context of failing to stand for the anthem.

According to FactCheck.org, NFL spokesperson Brian McCarthy said that the manual encourages players to stand during the anthem. However, McCarthy told FactCheck.org that players are not required to stand for the anthem. That's coming from the league, which means if there is a rule requiring players to stand for the anthem, even the league doesn't know about it. It's apparently only a rule that Trump is familiar with.

The weird thing is, even Trump himself acknowledged that there isn't a rule. He did that by saying the NFL should change its current policy, which implies that he believes that there currently is not a rule requiring players to stand during the anthem.

Sports fans should never condone players that do not stand proud for their National Anthem or their Country. NFL should change policy! — Donald J. Trump (@realDonaldTrump) September 24, 2017 ...our Great American Flag (or Country) and should stand for the National Anthem. If not, YOU'RE FIRED. Find something else to do! — Donald J. Trump (@realDonaldTrump) September 23, 2017

Jeff Sessions, the U.S. Attorney General, also advocated for a rule change during an appearance on "Fox & Friends."

"I think it should be a formal rule of the league," he said. "They should be able to say to the players, 'If you're on our field, in our game, paid by us, you should respect the flag and the national anthem.'"

The protests against racial injustice began a year ago when then-49ers quarterback and current free agent Colin Kaepernick remained seated during the national anthem and pledged $1 million to charities that help communities in need. Several players around the league quickly joined Kaepernick's protest. His protest lived on this year through players like Michael Bennett. But the protest changed in recent weeks once Donald Trump made inflammatory comments about players who kneel during the anthem.

"Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a b---- off the field right now," Trump said Sept. 22. "Out. He's fired. He's fired."

"You know, some owner is going to do that, he's going to say, 'That guy that disrespects our flag, he's fired,'" Trump also said. "And that owner, they don't know it -- they're friends of mine, many of them -- they don't know it, they'll be the most popular person for a week, they'll be the most popular person in this country, because that's a total disrespect of our heritage, that's a total disrespect of everything that we stand for."

In a show of unity against Trump, the majority of teams planned demonstrations during the national anthem. Some players refused to stand during the anthem, many linked arms, and a couple teams didn't even come out for the anthem. Those in the latter group weren't fined by the NFL, according to CBS Sports NFL Insider Jason La Canfora.

The Cowboys, on the other hand, decided to kneel before the national anthem. They then stood up during the anthem. Now, we likely know why they did that. If they had all kneeled during the national anthem, they wouldn't have been able to field a team.